I have now done the switch, the test charge setup was successful and my app now says Octopus will create a Smart charging plan after 5pm.
However I haven't received an email telling me that I am moving to Intelligent Octopus, both app and Web account still show Go Faster & I'm unable to call their 0808 number (even with +44 808) to query.
When/how did you receive confirmation? The rates were shown as I signed up but haven't appeared since.
By the way, my Go Faster plan was due to expire next Tuesday 11th anyway so this is timely to lock in 5p as the second car will increase our night rate consumption however I charge it. Apart from oven/hob/ironing* almost all other devices in our home are either battery charged overnight or on overnight timers.
*I tried working on a betaWife overnight plan for these but it didn't go too well.