Overall your plants look healthy and happy, never grown from seed before, but I know with clones, you usually don't see a growth spurt until at least week 3 or 4 of veg...
I would recommend raising the humidity to at least 30% or higher...when the humidity gets this low in veg, sometimes it may slow the growth down slightly because the plants go into a sort of "drought" mode and slow down intake of CO2 and uptake less water. The ideal IMO would be between 35-50% for veg.. and 20-45% flower...
I've noticed with temps I try to keep mine below 85F but some strains show stress when I hit around 80F, some are fine at even higher temps... just watch your leaves and if you see them start to roll up like a fresh split blunt, then you know there stressed due to heat and dry air... if not..then you should be good