Yeah, my LCS didn't have the rings first day, either. I had to save my receipt and come in the next day to get it.
My LCS is also the lesser of two stores in town owned by the same guy, and all the rings came in at the other one. I think they pooled orders between the two locations to hit the quota required to order them. If yours was a chain, maybe a similar thing happened and they're at another location? (this was really the only ring i care about getting, though, so lucky for REBELS)
Though I've gotta say, I think this was a good example of how tie-ins should play things. So little of it was actually devoted to the actual Blackest Night tie-in that the outsiders coming in get a good dose of what REBELS is about, and might be more likely to stay, which is exactly what a struggling title like this one needs. The more I think about it, the more I like it, and the more I'm thinking I should follow this title every month.