I picked a shop that was flexible on the DM training. Everyone in my class was a mature student and we all had full time day jobs. We would keep in touch via email and arrange for evenings to get together and go over the course material. Usually Thursday nights for DM classes. Friday nights was attending OW classes. Saturday and Sunday was working in the pool with the OW students and watching the Instructors (and other qualified DMs) teach class.
On weekends we didn't have OW classes we would work with our instructor on skills (making them presentation quality), do the stamina tests, perform the 20 basic skills, etc.
When OW students were doing their check out dives, we would join and do grunt work (set up tarp for shore dive; haul instructor's tanks; etc.). We'd follow along in the water, etc.
Helped out with a number of Discover Scuba Diving sessions. Mostly kids. Interesting to see how a little horse play can get some kids into trouble and how the instructors dealt with it.
Spent a year doing all this. PADI is processing my DM application right now. Should have my card in a few weeks. Going to be a DM for a while. Get more diving in and experience dealing with different types of divers. I've seen a wide range of divers (young to old; comfortable to nervous; cautious to risk-taker). Still working on being comfortable around all of them.