What day and month did dean get dragged down to hell?

I only now the month and that was May when he went to hell :S

But he got dragged out of hell by castiel if i'm not mistaking on september the 18th :D

i only know it was may but i know it sept 18th when he got out because its just before my birthday

I think Dean got dragged out on september the 18th.

From may to sept. he was in hell 4months. Dean said that it was 40 years in hells time.

September 18, 2008 (according to newspaper he picks up in Lazarus Rising)

He was dragged to Hell on May 2nd, Sam's birthday.