I was just playing Aliens: Colonial Marines when the question just popped into my head.
When is the game set?
The AVP Wiki timeline places Aliens: Colonial Marines in the year 2179.
The game takes place in 2179 and is a sequel to the 1986 film Aliens and takes place after the death of Ellen Ripley in Alien3
Noting that the in-game profiles show Peter O'Neal as being aged 31 years of age when the game takes place, that puts the events of the game sometime during January or early February 2179.