I just finished eating. - should be Present Perfect here (but in AmE Past Simple is also possible) I already finished eating. - same as for the 1st sentence Once you finish eating / or Once you've finished, come over here. After I've finished eating, I'll come over. - You can also say, "When I finish.." Can't you just wait until I finish eating? - both sentences (including the next one) are correct Can't you just wait until I've finished eating? - Have you finished eating your lunch / dinner?