I veg for 10 weeks, a week or so to root clone, 2-3 weeks in 1 gal, 4-5 weeks in 3 gal, transfer to 5 gallon buckets around beginning of week 9. There as big as SouthCrosses, but i train for multiple tops and even canopy. When there done I can pull all my dirt as one giant ball, save for the bottom couple inches. I still need to water every other day usually, unless I really soak them, then I get 2-3 days.
VEG time,veg lighting and plant size going into flower will dictate final pot size. I'd say if you keep veg time around 6 weeks, 3 gal would be good