Depends. If they call you today for an interview next Tues, you'll probably be SOL on interview prep. I'm sure they're all pretty busy right now...

Unless you know that all the places you've applied will give you at least three weeks notice, I'd get the interview prep done sooner rather than later. They will all provide a last-minute "touch up" consultation once you get the interview.

Also have the tailored suit, logbook, biographical documents, and deep technical study all done in advance, so you can focus on research/prep for the specific airline when you get the call.