Put the dot exactly on the spot you want to hit. The dot is a nice, bright, sharp thing and putting it directly on target will feel intuitive right away. Distance is up to you, but for a defensive pistol, I feel zeroing the dot at 15yd is a good spot. Good for close distances and still good enough if you need to reach out a little further, for whatever reason. There are different opinions on what distance you should zero your dot. Some say "It's a defensive pistol, you're not a sniper, keep it close" or words to that effect. Others say "There have been examples of people needing to take defensive shots at greater distances, so prepare accordingly". I'm more in line with the latter, but it's up to you.

As far as the iron sights go, I think Springfield sets up all their guns to have a 6-o'clock sight picture (all the XD variants I've owned, anyway), but your owner's manual should tell you for sure.

Finally, whatever you end up choosing, make sure you test to see if each individual set of sight performs as you want. In other words, if you get your red dot right where you want it, don't just adjust the irons to match assuming the POI is the same. Depending on how you hold the pistol or how your eyes perceive the sights (I'm talking minute differences) there may or may not be a slight difference.

 

You just line up the dot at the target and adjust to you. Your eye and the dot and the target are all that matters. The iron sights are only a backup.

 

The red dot and the irons should be treated as 2 separate sighting systems. You shouldn't need one to use the other.

The factory irons on my hellcat are setup so POI is just below the sight picture at defensive distances. I adjusted my red dot to POI at 7 yards. When I'm using the red dot, the front sight is way above the rear sight. When I'm using irons, the red dot isn't even visible.

 

I only have experience with red dot sights on CZ pistols, so far.

Happens, on two of mine, the point of impact for the irons and the red dots are pretty close at 12 yds. (within an inch, or slightly more, with the POI for the iron sights being slightly lower than it is for the red dot.)

When sighting in/adjusting the red dot I try to center the dot in the lens. Same for just putting holes in the paper. You can take your time and center the dot in the lens with the dot on the place you want the bullets to hit on the target.

I've done this with my RMR DI sights to prove it to myself after getting the RMR sighted in.

Shot 1 - dot along the left side of the lens, but on the center of the target, too.
Shot 2 - dot at the top center of the lens but on the center of the target, too.
Shot 3 - dot along the right side of the lens but on the center of the target, too.
Shot 4 - dot at the bottom center of the lens but on the target, too.
Shot 5 - dot in the center of the lens and on the center of the target.

All 5 shots were in a nice group in the center of the target. Had to prove to myself what I'd read on another forum. As long as the dot is where you want it on the target, the dot doesn't have to be centered in the lens. Try it next time you go to the range though, to make sure your sight works on your pistol like the RMR DI sights do on my two CZ pistols.

One other point. If you have a fiber optic front sight the same color (say, amber) as the dot in the lens of the red dot sight and that bothers you change the front sight fiber optic color. This doesn't bother me at all. Bothered the heck out of my wife. Her CZ75 Compact and the Leupold Pro both amber dots. I put a green fiber optic rod in her front sight and she was happy as could be with it.

On both my RMR'd CZs the front sight and the RMR dot are pretty close. I've found I don't even pay attention to the front sight unless I want to shoot the back up iron sights for confirmation they are still sighted in.

On my P07 with the Holoson red dot the front sight is well below the amber dot. Again, I don't notice that unless I'm looking to shoot the iron sights.

 

If my irons are on point, then after mounting the red dot, I align the dot with the front sight to get it close.
Then micro adjusts at the range insure the red dot is on point.

 

I'm a newbie to red dots so if this sounds clueless it's because it is. I zeroed the red dot at 12' because this gun is my EDC. I had a feeling the red dot is the POI so my thought was why not zero it exactly at the aim picture of the iron sights so that my natural tendency is to point using iron sights and confirm with the red dot (and do all of this within seconds).

There's only one issue with this setup...the dot is lower and sometimes more difficult to find immediately.

 

Using the red dot to confirm irons pretty much negates their main benefits. That being, the speed improvement from not needing to align sights, and eyes focusing on the target alone, instead jumping between the front sight and target.

 

The dot will float so it's visible throughout the entire window. Ideally the dot is centered in the window, but at these close ranges, as long as the dot is visible and covering what you want to hit, your all good. My irons are barely visible at the extreme bottom of the window and if I line the irons on target, the dot is right there in line too. Now if I center the dot to maximize the field of view around the dot, my irons end up below the dot at the bottom of the window and out of the way. This is normal.

What you don't want is to be lining up two sighting systems when you go to take a shot. This requires too much time and mental focus. With an RMR, focus on the target and getting the dot to cover where you want to hit right on your initial presentation. You should not be "sharing" focus like traditional irons where the target and front sight are both partially in focus.

Dot approximately centered in window leaves irons low.

Irons lined up showing dot absolute co-witness.

 

The dot will float so it's visible throughout the entire window. Ideally the dot is centered in the window, but at these close ranges, as long as the dot is visible and covering what you want to hit, your all good. My irons are barely visible at the extreme bottom of the window and if I line the irons on target, the dot is right there in line too. Now if I center the dot to maximize the field of view around the dot, my irons end up below the dot at the bottom of the window and out of the way. This is normal.

What you don't want is to be lining up two sighting systems when you go to take a shot. This requires too much time and mental focus. With an RMR, focus on the target and getting the dot to cover where you want to hit right on your initial presentation. You should not be "sharing" focus like traditional irons where the target and front sight are both partially in focus.

Dot approximately centered in window leaves irons low.
View attachment 833501

Irons lined up showing dot absolute co-witness.
View attachment 833502

I get what you're saying. Center the dot in the screen so it's easy to find and not have to mess with a front back alignment. I'll give that a try. Should be faster to acquire the target.