Grow tent questions - Beginner grower

Hi guys, I am currently at the early stages of starting my grow, germinated from seed, 5 in total, 2 of them look real healthy and strong, 1 of them I would say looks healthy but compared to the other 2 bigger ones it isn't doing as well. I have 2 that look kind of weak, I already lost 2, probably because I made an error when germinating and put them firstly in moist soil in the sun for a few days and the soil kept drying out, moved into the bathroom in the dark and within 3-5 most had sprouted, guess I lost a few due to the newbie error.

They are lemon bubble autoflowers which I bought in Amsterdam

My setup is as followed tent size is approx 1.2 x 1.2 it'skind of small, thinking of growing 3-4 plants in there which means that 1 or 2 will have to go, more than likely if the weaker ones dont make it, I'll use the 3 strong ones.

I have a 600w MH for the vegetation, 2 x extractor fans 4 inch, inline and outline, a fan keeping the air moving, and an AC unit positioned outside of the tent (It's summer here, without the AC it gets to around 90 faranheit, its summer here...

I dont know whether I am watering them correctly either, I'm using power roots and alga grow for the basic nutrients, but they're in small pots, next few days I'll probably repot them, just waiting for a solid root structure,

How many times should I water them? should I wait for them to completely dry out or just keep it at a relatively moist level?

The temperature is also hard to gauge, I have 2 tempt readers, one of them between the plants which always reads 27/28 celcius, and one at the top of the tent which always reads 22/23 the same as I have the AC set on..

18/6 schedule was told it didnt matter as they were autos, but others said it does matter, would be idea to remove the AC unit if possible, maybe suck some air from straight outside where at night it's around 20 degrees celcius and get rid of the AC which will probably end up costing a fortune along with the 600watt light..

Any help appreciated

Thanks guys

Pictures of what you're working with can greatly help with visuals/logistics of your setup. Baby seedlings are pretty thirsty and as long as you have a well draining medium don't be scared to saturate their pots(as long as you aren't using massive pots) but be sure to let them dry out almost completely between watering.

18/6 is fine I would probably go 20/4 with autos though. You want your thermometer away from direct light and away from the A/C vent. Maybe hang it up in a corner somewhere. Sounds like your tent is running a little on the cool side

EDIT: take advantage of lower night temps and run your "lights on" during the colder parts of the day