Take one day and only ride switch. Strap in switch, get on the lift switch, get off the lift switch. This is how I learned it and it worked well, for me at least.
I don't think you need to learn how to ride switch early on. I learned after I was pretty good riding normal stance. If I'm going to say something on the subject I would say learn switch after you're a solid snowboarder in your natural stance. Then you already know how to do it so I think it's easier.