Was there last night. Got to the Poly around 3pm, no one was in line in the hallway waiting. Line started to form by 3:30 and I was 10th in line. After the initial rush of guests entering and pushing the place to capacity, people were checking in at the booth and were told immediately an hour and a half wait, not even five minutes after 4pm. Makes sense, since we stayed in there about an hour, so you could assume that most parties will do the same, at least.
Similarly, I was there at the end of May, arrived around quarter after 4 and was also told an hour and a half wait. Got drinks and food at the Tiki Terrace and our pager buzzed after only an hour. Like others have said, we entered and there was literally no place for three people to sit together. We initially sat two at the central surfboard, and one joined another party at an adjacent table. After about a minute, space for 3 opened up at the other end of the surfboard and we relocated.
But it's definitely a must-do for us -- we will just always get there before opening. I'll probably be back there again tonight or tomorrow. And yes, the Nautilus mug is back in stock. "We learned our lesson", we were told.