i feel like a dad watching my baby take her first steps. lol

This is my first ever grow so yeah im a rookie but from alot of you guys ive taken the necessary steps for a successful grow. im a lil worried about the next two weeks though. its day 12 of my autoflowering and i know soon i should be adding nutes ive heard a million people say a million different answers. some said i can add nutes next week some said wait atleast a month. ne suggestions ??

this is the run down
soil- ocean forest fox farm
set up- 5 6500k (26 wt) cfls
seed- sour diesel




by the way can any one tell me why my middle leaves look kind of yellowish should i be worrried?

thanks for the help