To answer the question if anythings time sensitive, I got the email two weeks ago and it said I had till May 29th to accept the offer. I think if you hear back later the deadline to respond will probably be later. That wouldn't be fair at all if they gave you the same deadline since you would get the acceptance email later.
That's odd, I heard back last Friday the 8th. I got in the HR program and got my email around 6 in the evening, do they send out decisions at different times?