If you have had thebestof something, you haveenjoyedthe mostpleasantpartof it, and everything that isleftisworse:
Ithinkwe've already had thebestof thehotweatherthissummer.
Itlooksas if it mightrainsoon- Ithinkwe've had thebestof theday.
With thepitchdeteriorating, itlooksas though theEnglandteamwill have had thebestof theweather.
It'sprettyclearthat he's had thebestof hispresidencynow.