Every so often a student admits something like this to me:
"In the first few sessions I was going to ask to drop out, because I could not keep up. But after a few more I understood how the class worked, and I was picking up so much along the way that leaving would have been a waste."
Why that feeling is deliberate
Feeling out of your depth in the early sessions is not a sign you were placed in the wrong class. It is planned.
At the interview stage I spend a long time talking with you, and I come away knowing where you are on your English. So putting you in a class that stretches you slightly beyond that is a choice.
Put you somewhere comfortable and you will not struggle, but you will be bored. And bored people do not learn.
Useful discomfort
That sensation of not quite keeping up in the first weeks is the thing that moves you forward. It forces you to reach, to listen harder, to come prepared.
What helps is knowing in advance that the feeling is coming, and that it does not mean you are not capable. It means the class is doing its job.