So is it correct that only LHR is bookable in advance, but not JFK? If JFK is not, how far in advance should we arrive to have a pretty good chance of getting in? It's an 1835 flight, and we plan on eating in the CCR, which could take an hour in itself I imagine? This will be our first First, so we'd like to take advantage of the whole experience.

Get there 3 hours early, check on availability at the spa, and schedule the meal around whatever time they can give us? Or would we need to get there earlier?

Do you have to walk from the CCR to the spa to check availability, or can someone at the CCR desk call or inquire for us?