It is preferable that you come twice a week for several reasons. First of all, every time students come to class, I can observe them work and give them whatever help they need, so the more often they can come the better. Additionally, the more often they come to class, the more frequently I can review their homework. This means that I will see right away if they need to review a section, or if they are ready to move ahead, so that your child does not get slowed down by unnecessary work or frustrated by work for which they are not yet ready. If students attend just once a week, it is much more difficult for me to predict how they will do, especially when they first join. Could you start with coming twice a week, and then we can see how it goes after a few months?