It is difficult to guess when your Tama will become an adult.
If you pause it one time only for 45 mins - then the evolution would not be delayed for long - perhaps another hour or two hours.
But if you pause the Tama for 45mins every lesson (math, geography, history, etc.) - then that Tama is on PAUSE for a lot of time during the day!
Maybe it will evolve tomorrow - late in the day - or perhaps the next day ... but I am only guessing! Sorry!
Best, etc.
TamaMum