Hi, you can train the pants at anytime really, just dont force sharp bends to fast as they mihgt get damaged.

my last grow I had to tie down the largest plant as it was to big during flowering.

They will however recover very fast and start growing stright upwards again, so you will have to keep an eye on them and tie down as nessesary!!

some photos or a good description of your space issues will help, how tall sre the plants now, how much height have you got lft to play with, and what strain?