You can flower anytime the plant is mature. Usually a good indicator would be alternating internodes or preflowers. Usually the alternating internodes are easier for people to establish it's "ready" to flower. Usually about a month old it should be good to go. Just remember they will at least double in size in flower. So, if it's a foot high going in it will be at least 2 coming out. So on and so forth.

Looks like your foliage feeding also. Maybe a off PH along with the foliage feeding is causing that droop. Maybe even overwatering?