My First Grow!

Sign it’s time to water lettting them droop between watering can be good. Water them they will stand back up and once they get enough water they will drop a bit again untill the water dries up then they stand up untill lose enough water to drooo again

It sure looks like underwatering to me... especially in such small pots - you've got some MONSTER leaves there which tells me the plants are going to be monsters, too! If these are photoperiods, I would transplant into a much larger pot (5gal? 10gal?) and thoroughly soak it... I'm thinking your roots are running out of room so no matter how much you water them in their present pots, they're not going to get what they need. I'd also raise your lights some - say up to 30" which will cut down on the heat they generate (giving the plants time to absorb the water) and will also encourage them to stretch... Good luck and enjoy the grow!