Always trust your gut...I mean spud. 3" of ice can be very good, very bad and everything in between, all dependant on a considerable number of variables.
For example...I fished a lake last year that was rising while I was on the ice. Easy to hop onto the in the am despite water covering the edges...by afternoon I couldnt jump to shore...and broke through trying to figure out how to plank off. (It sucked)