To fix the problem in future: the light is not strong enough. You have a very stretched-out plant. Long internodes...
As far as when to snap a branch down... more than one factor to consider. If growth has stopped, it's easy to pick a spot and level it out a proper distance from the light. Expect the top portion of anything you snap down to culr upward 90-degrees..It'll regain maybe 5-8 inches of height will, so consider that when choosing where to snap it down.
If it's still growing, you may have to snap it twice or snap it a bit lower than you expect to mitigate future growth to avoid doing it twice. A moving target in that context.
The first time i snapped a branch, i did get some leaf droop, meaning the vascular tissue was damaged a bit too much. When you do it right, you won't even see the leaves droop, which means the vascular tissue is still pumping water and nutrients to the stretch of stem above the snapped point. Either way it'll heal within 24-48 hours