Another Fermentation Question

My buddy and I brewed Sunday and put both fermenters in my temp controlled fridge. Mine in a plastic bucket and his in a glass carboy. Mine has taken off and his has not. No krausen, no bubbles, no airlock movement. It also looks as though everything has sunk to the bottom of his carboy. So when I got home today I turned the temp up a tad and shook the snot out of his carboy. It's been a few hours now and everything seems to have settled back to the bottom? I am thinking about throwing in some yeast nutrient, since he doesn't typically use any. Is is too late for nutrient? Any suggestions? I know it can take up to 72 hours to show signs of fermentation, but this is the first beer he has made where he is able to control the ferm temps and is really excited, and since it's at my house, I'm trying to help him out. RDWHAHB I know!

First question: what was the OG, and what's the current gravity.

You say it hasn't fermented, but without a gravity reading you don't have conclusive evidence.

Also...it hasn't been 72 hours

I know I know I know...that wasn't the point! hahaha I'm really just wondering if adding nurtrient after the fact is good or bad. I do not know for sure that it has not done anything I just know that there are no visible signs of any fermentation.

Adding nutrient after the fact is not "bad", but it most likely won't kick start the fermentation either. If it needs starting. Other than that, what malkore said.