How long do clones take to enter veg ?

I consider them to be in veg phase when they start growing roots through the bottom of my rock-wool cubes. That may not be the correct definition but that's when they start their growth spurt I find. This takes 2-3 weeks for me in a warmed dome chamber with rooting gel. I would suggest letting them grow 3 or 4 new nodes before you start taking any clones off them. This is about another 1-2 weeks after the above is complete.