wedding planning timing

[spotty4]

I'm at a little bit of a crossroads regarding the little bit of wedding planning on our plate. About 65% of the guests on our lists are out-of-towners. I estimate easily half of those folks won't come out to California b/c of distance/time/cost etc ...

We're mailing out "save the date" cards next week and I know that some people that do plan on attending would like to get their travel arrangements in order sooner rather than later. W/ that in mind, I'd like to have hotel information available to them (i.e. one or 2 local hotels that have reserved a block of rooms, perhaps at a discount rate).

Is 6 mos out too early to call on hotels for this service? And how do I estimate the number of rooms to block if we're not even sure on attendance (too early in the game for official RSVPs)?