Depends on your situation. We're IB for Maury and will not apply elsewhere if we like PreS3 at AppleTree LP, as we expect. Maury has to take us for K but didn't have room for us for PreS3. We would like to stay at AppleTree for two years and don't expect Maury to have room for us in PreK4 anyway.
We know Brent, Peabody and other Maury IB families in similar circumstances. It sounds like 3 year-old refugees from the long IB wait lists from the three schools will flood AppleTree LP this fall (meaning more high-SES kids than this year).
Those shopping for a K-5 charter will surely still shop!