Valve said last month that it was "confident" Half-Life: Alyx would not be delayed past its targeted March release,
Valve Announced that the VR Half-Life 2 prequel will be out on March 23.
The Steam page lists it as just March 2020, but that's the official Valve Twitter feed. Valve also dropped a screens from the game and it looks amazing!
Those who have purchased Valve Index VR rigs, preorder bonuses will start going out during the week of March 2, beginning with Steam VR Home environments inspired by Half-Life: Alyx locations. More information on the availability of the Index and related hardware (which are still out of stock across the board) will be announced "soon."