First time growing an auto plant so any advice is appreciated. I’m on day 19 since seed popped out of soil. I have my plant growing in a 10gal pot with fox farm ocean forest. I’m watering twice a week with plant marvel and once a week with Humic/fulvic acid + seaweed extract.
Your doin great so far! They look happy. I would make sure an not let em get completely dry for too long a periods. Dont want em soggy soaked either tho. There are several strategies IMO for groin autos. Are u growin for speed? Want it to.finish ASAP? or u aiming for size and speed? I top mine afoind the time they get 2cnd or 3rd set of leaves. Thsy will bush very similarly to photos but it adds up to possibly 3 to 4 weeks extra to their finish date. Dont advise feeding any nitrogen. I give mine nothing untill theyre half way.thru budding.an.then i only use cal mag.
Looking good 
, see above 
Did you add more perlite to the ocean forest?
Be careful watering so young in a big pot…once a week be good now! Good watering this young will last 3-4 day unless ur watering till runoff everyday.you doing high firtigaton multiple times a day say every 6hrs do a feed?!
About a third of the pot is a 50/50 mix of perlite and coco mixed in with the FoxFarm. As for water I do monitor the soil and only water if needed. We have had rain for the last 3 days so garden watering has been on auto pilot!