The A-10 thing was a good idea.
To try and answer it serously...
Over my own home town Riverside, CA. It would be a while before they were shot down. even though we have an AFB with ANG F-16's they're out on the tarmat in plain view. so if the Warbirds started thier attack by straing the F-16's on the ground they would buy themselves an exatra hour or so.
I imagine it would take tha long for fighters to scarmble from one of the other close by bases and get here. Maybe 2 hours depending on how long it took for the right people to understand that it was for real.
Ove my old neighborhood in Los Angeles. not very long. Most of the population is straped like Iraqi terrorists! They shoot at police helicoptors, they shoot at news helicoptors, heck they even shot at the alien shapcecraft in Independance Day. They'll definately shoot at some warbirds srafing the local kindergarden. Hahah I can definately see my grandparents sitting on thier back porch balcany with thier rifels. Just rocking in thier old chairs and blasting away!
Hahah you can take the southerner out of the south, but you can't talke the south out of the southerner.