I wouldn’t get a new e10 installed then switch the next day/ week.
This is exactly what I did and the meter never got placed on to the national database. I had over a year of hell trying to sort it out. If you do get the meter swapped, definitely wait for it to be registered then switch. It could take a couple of months.
Just digressing also. The main reason for my e10 is because I have solar panels and an electric car. Octopus energy are doing such a great night rate for ev’s (Electric Vehicle’s) 5p kWh from midnight to 4am and 14p kwh during the day that I’m even considering going to a smart meter.