Major props to emilya for that post. I forgot all about using LST to keep the plants short while vegging. This will indeed make it more practical to start the screen when switching to 12/12. This of course will depend on using the LST in such a way that you can indeed easily move the plants without damaging them. I too have found that having the lights slammed as close as possible to the plants during veg will shorten overall hieght by reducing internodal stretching. This assumes you can deal with any heat issues.

CanGroit, I forgot to mention that you will get fewer and less productive bud sites due to the lesser effect of the light on the lower sites during the unrestricted veg period. LST during the veg will help overcome this tendancy however.

regards,
Max Blast