I'd give em a week or sooner, till startin' flower. They're lookin really healthy. Gotta remember they gonna be 2 to 4 times their height at the end of stretch depending on the strain. They gonna start growin crazy once you switch so, make sure you don't veg em too big.
You can also bring the light way closer using your shelf there, 4-6" away is good, you can get real close with cfl just watch em to make sure it's never too close. Use the back of your hand to judge heat by leaving it there for a while.
Oh yeah, the 48 hours straight is just fine, some ppl veg round the clock.