Left the trailhead at just after 6 am in the dark. Cold temps (mid 20s) with forecasted high temperature at the river of 67 degrees. I reached the river in just over three hours (probably should have taken it a little easier as I was pretty beat up already). I was following the gpx file that was posted here on the FKT website, and near the river the route was all messed up. I think someone just drew in a line on the gpx file to get to the river, but when I followed it I got all tangled up in some mesquite before I decided to head over to Nankoweap Creek and follow it down to the river, which makes for a pretty natural turnaround point.
I stashed water at a few spots on the way down so I'd have them on the climb back out. Treated water at Nankoweap Creek with Aquamira at a few spots. Drank a total of 256 oz (2 gallons!!) and didn't pee all day until the drive out from the north rim at Jacob Lake.
Steepest part of the route is from the saddle up to the upper Saddle Mountain TH - oof!