Nyc auto first ever grow

Couple brown leaves not sure what's up + one NYC Diesel seed hasn't sprouted yet so I'm not happy about that, lil bastards hiding in there somewhere. 22/12 the new guy sprouted, he's a week behind but he will get there. Watered on the 23/12 and again today on the 26th. No nutes yet as the leaves are just recovering. So far watering ever 3 days with plain water, one plant has gone brown on the leaves, looks nice but unsure if it's normal as the other one same strain. Is a week or two behind but full green. 3/1/2020 this guys growing badly, still watering every few days but its looking like a phosphorous deficiency and im not sure how because im not soaking the pots and im not starving them to my knowledge so im waiting to see how it goes from here. trying to source information however alot of people seem to have no idea what is going on even the dude at the hydro shop had no clue and one person said either over watering or inconsistent watering however i always go via the rule of thumb if its still moist 2 inches deep its still fine for a day or so and i do check every 2 to 3 days. Good thing i got two of them down at the moment incase mr purple there doesnt make it. ill add photos to week 3 as its officially week 3 today.