There's no specific time set but the update is coming to PC gamers this week, it'll include unlockable weapons for classes.
The Medic gets the treatment first and the new map Goldrush introduces a new mode which has one team perilously escorting a rail cart.
The Medic weapons are unlocked as players reach achievements; they are upgrades from the standardised weaponry and offer neat bonuses. The new mode requires one team get the cart to the other teams base, the more blues around the faster it travels.
Eventually these updates may hit the consoles but it’s unclear when at this time.