You can but your gonna kill your yield by topping that far into flower.You can do lower stem removal and top plants up to 3 weeks into flower on a 9 weeker. Best to do it all by the end of the second week. Imho
Tell that to those guys with the huge threads running aptus. Jack may offer does exsctly that. He tops and does lsr for the first 3 weeks and gets 2.5 per light. I get 2 or close everytime. Not sure what your yields are..
aptus is an additive/growth accelerator
it does make for some pretty generous buds and it does 'work' but as i mentioned it is not approved for food crops ~only ornamentals
so; pretty pictures of shitty tasting toxic buds
Dumb question how long does it take to flower on average if there is one