How tall is too tall to FIM?

Title says it all, I have a plant that is outdoors under sunlight she's 19 inches tall right now, a pretty healthy looking plant, although she's bendy in a couple weird places because i failed at LSTing her. Maybe 1 - 2 weeks till i send her into flower.

Nobody? btw 1 day later she's 20 1/2 inches tall now XD

the idea is to do it when the plant is young. once it's a certain height and age, it stops making any sense to cut off growth tips. typically any kind of training should be done early on in the vegetative stage

FIM her let up know what happens .... you have plenty of veg time left