XWvTF timeline

The game Star Wars: X-Wing vs. TIE Fighter and its expansion Balance of Power Campaigns do not provide any information about their timeline other than it takes place during the Galactic Civil War between the Galactic Empire and the Rebel Alliance (2 BBY ― 4 ABY). Nevertheless, some clues permit to place the game and its expansion around 3 ABY. X-Wing vs. TIE Fighter shows the Empire making extensive use of TIE/ad starfighters. The previous game of the series, Star Wars: TIE Fighter, established that the TIE/ad starfighter was introduced during the Sepan campaign (which is set in 3 ABY per the reasoning here). We can conclude that the game is set between 3 ABY and 4 ABY. Moreover, the most advanced Imperial starfighters from Star Wars: TIE Fighter (the TIE/d "Defender" starfighter and the Missile Boat) were not present in X-Wing vs. TIE Fighter, suggesting that the game takes place before their introduction, also dated to 3 ABY as the entire TIE Fighter game is set in 3 ABY (per the reasoning here).