If he's already rubbing on things, then his eyes would be clear. They go blue for a few days, clear up for a few more days and then they shed. So, if you missed the cloudy-eye period, they only way to tell that they will shed is by the dull appearance overall.
If you think he's having trouble getting the shed started, it may help if you make him a moist hide. Take a plastic container, cut a small hole in the lid and fill the inside with moist paper napkins...this way, he can go in, soak himself and rub on the moist napkins to loosen things up a bit. 