Stolen plant, I'm gonna miss you

I'd say wait until she has 5 pair of leaves and you want to top a healthy plant growing vigorously, if she is having problems growing you need to wait at least 7 pair of leaves before topping, good luck ! It isn't risky as long as you wait for her to be able to grow out of it ! :) Also I'd recommend mulching the top of your soil for beneficial soil health and 80% less watering! :)