I talked to a guy while fishing in the general State College area this weekend who was fishing Kettle the previous week. I can't confirm the accuracy, but he said they fished to great BWO hatches up there! This would have been the week of 5/4. If accurate, that should give some reference as to how far the hatches are behind. Normally, I'd expect to be fishing Hendricksons on Kettle in early May, while up for Turkey.
I fished Kish, Penns, and Spring this weekend, and all seemed to be behind in terms of their bug activity. Penns had decent MB's and Sulphurs, but not a lot, by Penns standards. Kish and Spring had only the occasional Sulphur, and basically no fish rising. No spinner fall on any of them. All were slow, but Penns fished the best of the three.
Edit: With things finally warming now, we may end up with a bug soup year, where everything goes relatively at once. Even this week is relatively cool for mid-May though.