I topped it with Optimum Car Wax immediately after application and it worked well.
Of course, I typically reach for HD Polish if I have a choice between Polish and Speed since you need to top Speed with something anyway to get any durability.
Just to play it safe I waited overnight and topped it with POXY--that was 3 months ago and the protection was still going strong, but I added another coat of POXY anyhow before the cold weather sets in.
Yeah, there have been a few that have had terrible durability, and some that have had "spectacular" durability. IMO, 1-2 months is all you can hope for unless the car is kept indoors.
You can top speed immediately, but its not really a product designed to top. If you were going to use a true LSP you would be better off using polish, then topping with Poxy or your favorite LSP.