We have a trip planned for 29 October 2015 - 6 November 2015, which means that we'll be there for the MNSSHP events on the 29th, 31st, and 1st. As we're the type that likes to take it easy our first day there, we'd rather not do MNSSHP on the 29th. So I'm wondering how hard it is to get tickets to the event on the 31st? Is it like trying to get an ADR at a popular restaurant, where you have to start trying to get tickets right when they go on sale?
It will sell out. I would advise buying them ASAP, but I don't think you'll need to call the very minute they become available.
Here is a link to a TP Blog about when tickets sell out. In 2013, MNSSHP tickets for October 31 sold out 27 days in advance.