<p>I never found preparing for classes to be too useful in general and for programming it seems even less useful since you’re most likely going to be spending a TON of time with the code either way, so the opportunity to learn it will present itself. The biggest problems with self-study, IMO, are most people lack the motivation to actually make meaningful progress over a summer and making sure you study the right material. While obviously some of the fundamental concepts carry over from language to language, spending a bunch of time learning about pointers in C is probably not a good use of time if you’re going to end up taking a class that uses Python.</p>