Hi there, I belive this is a auto plant, so taking that in to consideration the tend to pre flower at day 28-30ish if not shocked to be earlier, so I would say you have 7 days left until pre flowers, take into account the healing time of a topping which is recommended 7 days, this will slow growth down at a vital point that you do not want, I would say leave it let it grow but its totally up to you. Haply growing my friend 💪💚