Funny you mentioned this, because yesterday I was scared that my Tamagotchi wouldn't evolve and therefore never get the matchmaker and proceed onto 91st Generation (this is my v1). I put my Tamagotchi to sleep and I don't pause them.
It was four years old as v1s take longer (my v4 evolved at the age of 3). By lunchtime I was getting quite nervous. I left it in my bag off pause and awake for the rest of the school day and it still hadn't evolved. Then after school, when I was going to the shops, I heard the evolution beep and it evolved into... my favourite character, Memetchi! I guess good things come to those who wait.
Oh, and it's also quite common for a v1-3 to change at the age of 3, and a v4/4.5 to change at the age of 2.