I know this is really late, but depending on whether or not you have started yet, this might help you. I studied my Masters in Special Education externally. Due to being external, I had lots of readings to do as I couldn't just sit in a lecture and be 'talked at' to get a lot of the information. Most weeks I'd probably spend 5-10 hours per subject studying. For about 3-4 weeks before an assignment was due, I'd probably spend 10-15 hours per week (per subject).