There is no definitive time, but it'll probably take a few hours to get from the trailhead to the lunch spot. My guess (and hope) is that everyone is aired down and on the move by about 10:00 am. If we move at a nice slow pace with a couple stops, we should be at the lunch spot around 12:30-ish (if we're having lunch where I am recommending). If we use my recommended spot, then anyone in the group can do as little or as much exploring or wheeling around that area as they want, or you can simply hang out with the group and enjoy food. The trails are all very simple with no major obstacles, but there are plenty of them zigging and sagging through the area to check out.
From the lunch spot, it will take about another 60 mins to get down to Hwy 62 in Yucca Valley (going through Pioneertown), and about another 90-ish minutes from there to get into the Temecula area (so roughly 2 hours back to Esco for you). If it helps, my plan is to hang out around the lunch spot for a couple hours and depart for home no later than 3:00 pm. That would put me home around 5:30 in Murrieta.
Joe and I discussed the timeline and several lunch spot options depending on the group size and how everyone moves down the trail. He has done an excellent job mapping out Plan's A through at least G.
The biggest challenge is knowing "exactly" or even "approximately" how many folks will show up at the TH, and then "guess-timating" how a big group moves through a trail like this.
People pace their trail driving differently, stopping for pictures of nature, bio breaks, stopping for pictures of obstacles, and finally...stopping for pictures of the group.
It is going to be a great day, and truly sorry I will be missing this run (w-o-r-k).
Thanks to Joe, Jordan, Steve, Tony, and Rick for attending and helping out. 
