Your only regret will be wasting a FP on splash that early. You won't need it as its typically a walk on in the first hour or operation.
Splash is my FAVORITE ride! And its our first ride of the day regardless of time of year. We frequently go in December. Going early means you'll dry off quick...especially if you follow up with a ride on Big Thunder!
That's what we call it to.When we did the Ultimate Day of Thrills tour they started with Splash first followed by BTMRR. They referred to it as the "washer and dryer".
On our last trip one of my rides on Splash I got more wet then I have ever gotten before. I was drenched, our entire boat was. It was during an After Hours and I don't know what was going on, but definitely super wet. A 2nd ride in that same trip we also got very wet (not quite as bad, but still very wet). It was summer