droopy plant need help

My Plant is about 3 weeks growing and sometimes it seems to be droopy right before dusk it gets 18 hous of light in the morning it seems very perky I water it every other day and give it only 1/3 of a cup of water no nutes yet there is some in the soil. should this be happening.

is there a temp drop at that time. is your soil dry be4 you water again. i give mine that once a week. you may be giving to much water sounds like.