Some people list future, predicted hours on jobs / activities that they know are guaranteed. Problem is, the "end date" for current activities is the day that you apply. You can't put on there that the end date is next March. (At least I feel like that is how I remember it being, someone correct me if I am wrong). Whereas some people put on the application how many hours they have with the end date being the day that they apply; also, some people do this method and then add in the description "*this is a currently active activity and I plan on receiving x amount of hours until matriculation.*"
What I suggest you not doing is putting hours on there that you did not complete. If anything, you can always update the school that you added "x" amount of statistically significant hours over the last "y" amount of time since you applied.
Things that look bad: schools checking your hours with your listed contact, and there being a large discrepancy; updating a school that you put on your application "x" amount of hours, but were unable to complete so its really "y" amount of hours.