Avgas Delivery....
I know that at my Aeroclub here in France we do not allow the use of our fuelpump within the first three hours after a delivery of Avgas as a very minimum. And only in the 12 hours after delivery if absolutely necessary, and whoever wants it is told about the delivery and asked if they really need fuel today due to the mixing effect that FFF states above.
In fact I believe that the 3 hour wait may be a rule in France.
Regards, SD..