Wattage for 4 Seedling Cups in a 4 x 4

I have a 400 watt Super HPS bulb and a 400 W MH bulb, and I'm trying to find the right wattage to use on 4 cups of auto seedlings for the first few weeks?

I already planned on starting out at about 23 inches distance and adjusting from there, but I wasn't sure about wattage in a 4x4 tent.

I know you don't want shock with autos, so I planned on cutting a hole in the cup and dumping her in the pot when they're ready for that.

Thanks

As a new grower myself take this with a grain of salt lol.

Both combined would be overkill for a 4x4 imo, But..
The MH has good spectrum for veg and then the HPS for bloom.
400w is fairly enough to cover 4x4.
You could run the MH till you see preflowers then swap to the HPS.
I read somewhere that some throw in a MH during flower to increase resin production due to the increased UVs it puts out .

Since you are growing an auto I see where you could go with running both lights at the same time but personally I would only throw in the HPS when they're starting to flower.
Running both could increase the yields if you can keep the temperature on spot.

As far as height I had some 4 day old sprouts under a MH at 24" height with no negative effects but this depends on reflectors because mine could focus or spread the beam.

Hope this gives you an idea , good luck

I have these under a 400W MH at 20 inch distance. Most of them are right at 2 weeks old. A few of them are a few days behind, so some are at about a week and a half. I have the light setting at 125W.

Would you recommend that I shorten the distance now, or perhaps increase the wattage at this point?

Looking good, I would increase the wattage and leave them at 20" but make sure your temps are no higher than 27C from the very top of the plant

You should really actually never dim a MH or hps. Although they maybe have dimmers on them it makes the bulb burn at a temp it wasn't designed to burn at. It's designed for 400w and create a certain spectrum with that power. Running under/over wattage can cause premature bulb failures/hot spots/blown bulbs.
Some better systems can be dimmed up to 65% but generally limiting power to the ballast would cause a poor lumen output and spectrum.
You should also always start the lamp at full power for 15-20mins before dimming if you choose to do so.

Instead, you should try raising the light up or consider using a smaller wattage lamp be it led or whatever until the plants get big enough. That way you aren't wasting power lighting up 95% of the tent with nothing in it.