What are you using to hold it down? I have a bushy plant I've been LSTing and I got a quarter of the way around the pot before i started flowering because It was already pretty bushy and I don't have much space.
You might need to do some trimming.

I'm using plastic tie cables to hold it down so it doesn't cut into the plant. I'm a bit cautious of trimming my baby as i'll probably kill it knowing me but in theory I'd probably want to start flowering in a month or 2 as I can raise the level of the lights to give it slightly more room.

__________________
Wondering if Anne Frank grew weed in her loft.

I just trimmed anything that was low and not getting light or bunching up near the bottom of the plant using a razor. Seems like it got bushier every time I trimmed it.

I use pipe cleaners to hook around the plant branches then I drill a small hole in the rim of the pot and loop a rubber band through that hole , connect the other end of the pipe cleaner to the rubber band. Seems to work for me.
You should be able to see sex of plant by the 5th or 6th branch node.