Too tall, what to do now?

How tall it will get depends on many things, but if it's a healthy plant then its height will be determined by genetics. I went through this on my first grow. Ultimately the GSCs were the only Sativa dominant ladies in my garden, and they stretched much higher than the Northern Lights they were grown with. I ended-up tying the tops down and with the main kolas forced to bend lower than the rest of the plant, I was rewarded with multiple kolas as the auxin was redistributed.

I’d just start LST now. Gently of course. If done right, there’ll be buds shooting off the back like a Dinosaur. Might be a bit late but I’d still try

You could cut the top, center/main cola off and then try and train the other tips outwards?

Hello, You could try and tie down whats pliable and then do a couple quick super cropping to the longest bits and then tie them so they don't straighten out. Typically a plant will double in size...sometimes more some less. I found the pinch and bend(super crop) is very handy. Good luck. ✌️

When you flip to flower, you can expect a 40-50% increase in plant size. You are definitely going to run out of room unless you bend her over and tie her down. I would have recommended to supercrop that plant had you still been in veg stage. Or at the very least, use some plant tie downs and try to flatten that canopy. Poke some poles in the lip of the 5-gal bucket and get some plant twist ties and hook them around the branches and pull them down gently until the plant is near sideways or spread out horizontally and not growing straight up like a christmas tree. For future grows in a space that size, I would highly recommend LST or even doing a SCROG. I have a 3x3 tent and exclusively do a SCROG setup for this very reason and I get huge yields for the small space. Check out my diaries, if you want to see what I am referring to. Good luck!