you're good to top.
make sure your scissors are clean.. I soak my scissors in 93% or more iso alcohol to disinfect.
I usually top 4 times before flipping to flower.
this is a nirvana blue mystic i just put into flower 1 week ago. she was topped 4 times and also lollipopped (taking off bottom 3rd of plant where shit nugs would grow).
any photo period strain I always do 2 things.. top multiple times and lollipop.. I dont do any lollipopping during flowering either .. I do all the topping/lollipopping in veg. then give it atleast 10 days to recover then flip to 12/12.
here is that blue mystic I have lollipopped and topped.
You'll get "Y" shaped branching after the topping works. that will look like this. Click to zoom in on the second picture and I show you what topping will look like after you've done it.