I've experienced similar issues. Something that helps me when faced with a random schedule like that is to try to impose some structure on whatever parts of the day are consistently free throughout the week. For example, if the earliest you have class is 10 AM, and the latest you have class is 4 PM, then think of 10 AM - 4 PM as your "random class time," where depending on the day, classes could fall sort of anywhere within that window of time. But if you impose some structure on your morning routine, and then maybe have a set time after 4 PM when you'll study and do homework every evening (say 6-8 PM, for instance), then hopefully that will make the random class time seem less stressful and chaotic. This type of strategy has worked for me, at least.