It's as soon as the text appears. Toontown is coded to reward almost everything before it actually appears done on the visible screen. When you defeat a flunky for a task, as an example, it is technically done as soon as the gag experience screen pops up. Example: Turning in Toontasks, defeating cogs, getting trolley beans, getting boss rewards, ect. So the final task is done as soon as the shopkeeper is talked to in technical terms.