Hey Buddy, if you're growing in dirt you won't need to add fertilizer anytime soon. Especially not to a little baby-sprout. Just water it. I'm doing organic dirt with water-only, which is a whole other bunch of Organic sites like The Dons, and some other guys who get really crazy with it. I just use Fox Farm and Dr Earth, a home-depot brand, and I cut it all with Perlite because dirt drains too slowly by itself. As your plant gets big start bumping up the growing container size. If you let that plant get a few inches tall and root-bound in the pot, bump up to a gallon, then maybe three gallon, to five or seven or bigger. The safest way to apply fertilizer (which I normally have done for the past decades) is to apply a tiny amount with every watering. It avoids 'nutrient burn', which is primarily from Nitrogen. Once you burn your plants it's tough to flush. By the time you see a deficiency or burn even, it's too late to do much. You need to be careful and avoid over-watering too. You can actually let the plants dry out and droop some if you want to be safe. Plants that get fertilizer every watering look good all the way through flower. Most of the plants I'm growing without added fertilizer still look fine through flower in 3-7 gallon pots.