No time is really TOO soon, but there's not much point in checking before the first week. You won't see too much in that time. I'd just wait till Tuesday or so. That way you might get a better idea on how much wax and brood is going on.
They'll go through more syrup after they grow a little. Maybe give it to them for the first month, so they can build up some wax. But after that they'll have more bees being "born" or coming out of the cells. More of the bees from the package will become worker bees, and do all the worker stuff.