all manoeuvres are carried out solely by reference to instruments
I think this is the crux. Our company mandates autoflight in weather below certain minimas. Surely you should be logging I/F if you need to log the approach for currency requirements.
For the original question. All the regs that I could find take flight (block) time for logbook purposes from the time that the aircraft moves under its own power for the purpose of flight until it shuts down after landing in the gate.
This means that all of us steal a little time when we get a pushback or take the time from doors closed.
Personally I'd select the second one as when the doors are closed, I am fully responsible for everything that goes on in the aircraft.
You are not logging responsibility time. Can your FO and FA's only log time from T/O?