Yea, that would be about the earliest I would do it fo an average size plant.
It depends on what you want in the end. I have topped sooner to make a mother plant.
I've had luck by FIMming around the 3-4 week of vegging, when they're about a foot in the little pots I use.
It's difficult to get it just right. Sometimes my trim only results in a 2-cola top and others end up with 4-5
center colas. Yum!
