transplanting question

i am growing in pots with a 50/50 mix of diatomaceous earth and hydroton, indoor grow. should i start with a 1 gal pot, then move to 3, then finally to 5 gal? or is it ok to have the plants in 5 gal pots from the beginning? thank you.

I grow all mine from seed in the final container being 5 gal. So yes its ok and advised, less chance of transplant shock if you dont have to transplant

Transplanting into it's final pot will undergo less stress than one transplanted more times. And why the hydroton?

Just grow it in one pot no transplant no shock and faster growth good luck