You don't have to FTFP...
You have a route, a start time, coffee stop, and a meal booked at the finish.
Things don't go smoothly - you don't start on time, there's a puncture, someone didn't bring their legs, something you go past is interesting...
It's worth reassessing as you go, there's nothing wrong with changing the plan to suit all the conditions of the day. Start the conversation with the group - others may have been thinking it, waiting for someone else to say something.
Sometimes a plan is just a rough guide.