Why wait? Top off now and pitch cool. The temp will rise up to where you want it within 12-24 hrs.
There's not one right answer, it depends, but you should be fine to wait for 12-24 hrs.. I chill all my beer in the fridge before I pitch, usually pitching about 4 hours after the boil.
In Process - Russian Imperial Stout, Nelson Sauvin Rye IPA, Mild No.3
In Kegs - Barley Wine, Apfelwein, Wild BlackBerry Wheat, Coffee Oatmeal Porter
Gone - so many :(