"It will be finished tomorrow" Well what the hell time is "tomorrow", because it sure as hell ain't midnight?

Yesterday I stayed up way too late, and started rebuilding the first Pokemon Center at around 2AM EDT. I assumed "it will finish tomorrow" meant midnight tonight, but when I got home from work (around 4PM) I decided to get a little busywork done...and it was finished. So what time of day is considered "tomorrow", because I've got 3 projects going that all say tomorrow?