FWIW, I was unable to get a boarding pass this morning, with two of us in the group trying at once, but were able to get one for (late) this afternoon.
Today was the first day I "practiced" and I was able to refresh and join right at 7am and go all the way to the spot where it tells me I have no park tickets for today so I feel confident that I will be able to pull this off with no problem when we go.