Southwest 737-800s?

Am I wrong, or weren’t WN’s -800s supposed to begin revenue service today? I even came across some picture online of a spray down, supposedly at KFLL, which would be Flight 1717 from KMDW…yet they’re listed as 733s on FlightAware. Is this a mistake, or am I seeing things and believing sites that are jumping the gun?

It was an -800 but showed up as a 733 for some reason.