I have a spare child in my house (he was an ex imaginary friend) and he was turned real late Friday, and Monday was the date of him (and the child that had him as an imaginary friend) to become teens. I had an adult who hadn't completed the skill challenge dealing with tutoring kids but who had a logic of 5 (it was Hannah Jones) tutor him, as I wanted to get him the chance to pick his own traits into teenager hood. He had family orientated, trait like Hannah, Hannah didn't have Genius trait or anything like that.
She started tutoring him on Saturday, it may have taken 4-6 hours to go to a B (he started right at the bottom), when I sent him off to play on the swings.
The next day I sent the whole family off to the park, and they engaged in further tutoring. It would have been about that long again, I think, and it was up to just below an A, I think, when I sent the family home. The next day, I sent him to school, he got an A and the chance to choose his teen trait.