It's your call. Tires cost money, and you won't get anything (will you?) for turning in the lightly used tires that came with your car, so it's all about how much you really want those Pilot Sport 4s.
Since they're summer tires maybe at least wait until summer? (Or maybe you're in a warm part of the country anyway - I'm looking at snow and ice out my window right now)
Personally I'm quite happy with the tires that came with my ST, while I do plan on going back to the Conti "ExtremeContact DWS 06 Plus" tires I've used on other cars for a while now when it's time to replace them, I don't see why I wouldn't just drive on these tires for at least 30,000 miles.