I don't recommend donuts as a pre-ride meal. Nor is skipping breakfast because you are running late a good idea. Don't ask me how I know this.
If the route is conducive to it, maybe each could ride at their desired speed with planned re-grouping points? Or stay as a group until a break off point for shorter/longer routes and join back up at planned point(s)?
Btw, not that it is happening here, but I've seen a lot funny math when it comes to cyclists calculating average speed. For instance, hypothetical "18mph ave", but still take three hours to move 36 miles.