The fictional ages of Nia and Booker

In the Raven's home episode "So You Think You can Drive", May 21 2021, Nia and Booker got their learner's permits. And I thought they were a little young for that.

Apparently in real life Illinois somone has to be at least 15 to get a learner's permit.

Booker and Nia's father Devon says they will go off to college in 3 years, presumably at the usual age of 18, thus implying that they are 15 in the episode.

So if "So You Think You can Drive" is in the fourth season of Raven's Home, and if each season covers about a year of time, it should be about three fictional years after first season episodes.

Any 4th season episode with a precise date, like a Halloween or Chrstmas episode, should be 3 years to the day after a 1st season episode with that date. The same goes for birthday episodes. The twins should be 3 years older in any birthday episode in the 4th season as in any birthday episode in the 1st season.

So Nia and Booker should have been about 12 in the first season. The first episode of Raven's Home aired on July 21, 2017, when Isaac Ryan Brown, born July 12, 2005, was 12 years and 9 days old, and so he should have been 11 when filming began.

And the Raven's Home wikia says that they were 11-12 in the 1st season, 12-13 in the 2nd season, 13-14 in the 3rd season, and 14-15 in the 4th season.

https://ravenshome.fandom.com/wiki/Raven%27s_Home_Wiki

But somehow I got the impression they were younger than that.