Usually not referred to in the past or present because it sounds pretentious -- only in the future tense.
2) "What are you doing after hours?"
3) "There's supposed to be an after hours at Moe's pad.
Incorrect: "We had a really good after hours last night." or "This after hours sucks."
"It was after hours so all I could order was this soda."
Jake: Hey man have you heard of anything going on after this?
Chris: Yeah there's supposed to be this kick ass afterhours at Christie and Jack's place.