Because I get up at the crack-of-dark every morning and don't really want to on Saturday, I'm thinking of starting the hike from the trailhead at 11am. (If you're coming from the valley, I'll probably leave around 9:15 and have room to spare...)
This should leave plenty of time to hike down and take some photos, perhaps enjoy a snack or lunch, hike back up, and drive back home in time to watch the Cardinals get destroyed by the Panthers.
I've never been there in winter before, and I'm not planning on swimming this time, but it is technically a hot spring, and 72° will definitely feel warmer than the air temp, so that's an option I guess...

[expecting sunny in the low 50s]