At this point, the French toast can be covered and refrigerated for several hours (overnight works well, it is ready in the morning). (alidaskitchen.com)
Let sit for 1 hour at room temperature or chill, uncovered, for up to 12 hours (longer is better; overnight works great). (bonappetit.com)
I find that having sweet potatoes submerged in some hot (hot enough to touch) water overnight works wonders. (nutritionfacts.org)