question on pots/roots

I ws wondering what size pots yall use during the stages of growth. I'm new to this, and right now I have 2 in 8"x5" pots, and 2 in 8"x7" pots. One in the 8x5 pot is 2 ft tall. I'm guessing with her I'll need to transplant her to a bigger pot for when I go to bloom. But at what heights/stages do yall look to change to a bigger pot? And do the roots expand more in vegie or bloom?

--Dash

 

I feel roots develop more in veg. then the energy moves to flowering when changed to 12/12. In my opinion you should never change pots. If your growing from seed start with a 5 gal untill harvest. Every time you transplant you stress the poor girl. You should beable to go strait through with the same pot. I dont use pots I found bed work for me. When I did use pots 5 gal were it. Pluss the biger the pot the less you have to water!!!