train them or top them within that first 3 weeks. normally around week 2 or so like day 20, they start to take off and grow more vigourously. if the plant seems super happy and healthy, try topping during that perioud or you can just use lst but after the transition period into flower or when there are buds forming, do not mess with the plant structure.
or if youre in a situation like yours again. then try to super crop and bend the branches into a 90 degree angle instead of topping which will remove future top colas. once flower is fully under way, she wont grow more branches and leaves.