Since you're still pretty new to all this I'd recommend that you just keep it simple. If you've got fem seeds I would plant them directly into 3 gallon pots. But if I remember correctly, you've got regular seeds. I don't like to plant those right into their final pots as you then use a lot of that expensive soil for males that will probably get trashed. I use 4.5" x 5" deep square pots to start mine. They are big enough for the first 3 weeks or so, until they sex. Then I transplant the females to their final 3 gallon pots. If I want to keep a male for pollen, I just leave it in the small pot. It will get big enough in it to harvest some pollen.