You'd be the first AFAIS. Have a good look at it by writing down the respective numbers before and after a game. Take a short single game, e.g. one shot practice at STA.
In my experience, one XP per shot is added immediately - you'd see the bar flash for a split second.
The game's total is shown in a window at game finish and added at the same time. It's a pity that the total XPs aren't shown in that bloody animation.
To be sure, return to the Main Menu instead of closing it down prematurely.