You can flower as soon as you want. recommended to wait until you have at least 3 nodes.

When the seed sprouts and you are giving your baby 16+ hours of light.. sheez a vegin'
Garden Knowm Reviewed by Garden Knowm on . When does...? When does the Veg stage officially start? Right when the plant pops up? Or what? When is the soonest I can put them into flowering? Rating: 5