Since it's already May, you should already be well into your training, and many events have already passed.
As far as the Vicious Cycle Gran Fondo series goes, Ephrata and Goldenale are in the books and the Leavenworth is 3 weeks away, so if you aren't already ready, you're going to be hurting.
It's not too late for some Ellensburg (June 16) bump and of course, the almighty Winthrop (Sept 21) is looming.
**Custom Training is available all year and is the best and most flexible way to go.
Here is a calendar of tons of awesome gravel events across the US, now go find one, come back here and let's get you toughened up for it.