Yes you can, but you better do it quick.
The cool thing about topping last minute like that, is the plant will something end up having 2 - 3 cola's inside 1 big cola. This happens because when you top that late, the plant still has another week or so of vertical growth left in it (depending on the strain) so where you topped it, the 2 new shoots just barely start to grow before they fully begin to flower and stop growing vertically.
Personally though, I try and get all my topping done before I go into flower to stress the plants out as little as possible as they begin their journey to flowering.