Depending on what type of ticket you're buying, I would consider getting them at your closest ITT before you get to Disney, as SoG has always, in my experience, had a very long line that moves slowly. Much of it is because folks get there and don't already know what the ticket options are, so it has to be explained to them.
We usually get the Stars & Stripes passes, so we have to buy them there after checking in, but next year we're going to get the Magic My Way with water park & fun options, since we need 11 days of entry. We'll just stay out of the theme parks for one day, and we'll be good. I'm hoping that one of the ITT locations in my area can order them for me in advance.