Best practices needed for Interest enrollment

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Hi, We offer some sessions that sometimes only produce a few enrollments. We would like to set up Interest Enrollments. Basically where a user could sign up and indicate they would like to take a class and once we get enough interest we would create a real enrollment and move those people to the actual session enrollment.

Would love advice on:

What pros and con's have people encountered in doing this?

How did you get around the start and end date requirement?

Does anyone know if the Min  and Max Seats can both be set to Zero? (ideally we would want people to be on a "waiting list".