Flowering too early?

[Brnwn4]

I have 21 plants. 6 were just transplanted from solos and 15 have been potted in 2gals for 3 weeks. I took the 6 just potted and 5 from the ones that have been potted. I plan on keeping the taken ones in veg and flowering the other 10 in a 4x4. They have roots coming out of the bottom of the smart pots. Can I start flowering now? All atleast a foot I’d say

 

[Old Salt]

You can flip at any time after they are above ground. It's a judgement call as to when to flip. Indicas will double in size, while sativas will triple their size during the stretch after the flip. I'd give it another week in veg since your plants look to be at least indica dominant.