IMHO, I would take the middle ground for a 3 change system and I'll elaborate:

1- rapid rooter plug for clone or 18 Oz "Solo cup" of soil for seed.
2- 1/2 gal pot for veg
3- 3 gal pot for final veg and flower.

Just be aware not to soak the bottom of the soil every time because it will stay wet much longer. Some give "half waterings" or just a spray surface watering to compensate for a dry soil top because you don't want to soak the bottom again. I'm sure it takes getting a feel for it. Less is more.
Ocotillo Reviewed by Ocotillo on . clone pot size I just finished rooting my first clones and already put them in 1 gallon and 1.5 gallon pots, 100% survived, but I once read that clones need less root space than plants grown from seed, can anyone tell me if this is true? Just trying to get an idea if I might have to transplant later, not trying to grow them too big though if I get an ounce off each I'll be fine. Rating: 5