You can anytime now. The canopy looks nice, and will fill wall to wall of buds. You don't want to cut it too close to the top. if you need more space after they stretch and the light is too close. if you have fan and or filter inside the tent. get it outside if you can. you can use the filter as a base and inline fan on top and as long as you have your duct tube connected to the top of the ten it will draw all the hot out from the top out. Nice work on training them short. i don't think you will run into any issues with light. Also blue spectrum light will help reduce stretching. hard to see leaf tips from this picture so a separate entry for that might help you out better. good luck!