@Pro Bot It just arrived (late), and I read it.
The only story in it ("Last Lantern Standing") is literally taking place smack-dab between the end of the film when Hal leaves Earth for Oa, and it's there he is talking with Sinestro about Abin Sur's funeral, a giant Manhunter shows up and attacks Oa, which they manage to destroy. It's directly before the game too, because Abin Sur's evil son is there and he isn't revealed as evil yet. He's having a toast with the other Lanterns right before the funeral and the comic ends.
So I'd put all that including the game as the day AFTER the final scene of the film (before the credits + before the Sinestro post-credits scene ofc). Not the same day, because at least take into account some degree of time dilation because it's dusk when Hal leaves at the end of the film IIRC.
April 1st.