From a fellow grower: I have a question I top my 3 weeks old plant it grew 2 top but I broke 1 top off will it grow back or should I top it again.
Mainlining you can top up to about 6 times giving 12 main colas
I usually fim mine 3 times, 5th, 8th , 12th leaves all get pinched off
You can top as many times as you like
The general idea is topping can be done any time so long as vegging will continue, the downside is it will temporarily slow down growth until the new shoot sites begin to take over. Typically it takes 2 weeks for the plant to recover from the injury and replace with new growth. Obviously that would suggest it unwise to top a plant within 3 weeks of flowering due to recovery time needed to create decent bud sites.