Big fan of shakedown rides!
Big fan of Spam too!
Make sure your rain gear is at the top of the pannier.
I always like to keep one powerbank (and cable) in my handlebar bag for charging on the go. Rough surfaces can disconnect things.
Other than the gearlist, a shakedown ride is great to test other things.
If using a gps device/phone stress test it by going off course, trying to navigate around some imaginary obstacle (online and off).
Have discussions about situations that arise on the road - it can prevent stress on "real" tours far away from home when people are tired.
Even if the country is familiar to you, try to perceive it through "touring eyes". Stop for photos just like you would far from home.
Not a bad idea to take a little time at the end of the day to record some notes from the day. It's amazing how much we can forget of a full day on the road. A smartphone is great for making quick notes or even voice memos.
And enjoy!
Oh! As said above, make sure you have a spare tube!