It totally depends, if you pause your tama it won't age as quickly, if the battery is low it won't age as quickly, there is not a set time it ages at, sometimes they age either in their sleep sometimes in the afternoon, anytime.
This depends - if it was born, say, at 12:00 AM, then that is when it is going to age. If born at, say, 5:00 PM, that is when it will age. If it is born, it will take longer than usual.