I read (in the bible by JC) that when ever you trim or prune your plant excessively like you are suggesting that you should wait a month before flowering her. Now I know you are slobbering for flowers and that seems like a lifetime. However, if you are topping due to height constraints better to top now then dealing with it at the end.
By topping and then flowering immediate you will hinder her flower cycle up to 10 days. You can also rub her stock or stem where you want to collapse her branch. Rub the branch 20-50 times between your finger and thumb till the stem starts to become mailable and soft when she is soft without breaks--- bend her over and tie her tip down. Also if you decide to top wait 10 days at least then total dark out for 36 hours then 12/12. should not prune for a month before flowering though.