Yes, that works. I haven't tested it in detail but I think that the audio signal comes through the cable as soon as the headphones are plugged in.
Not sure if the headphones can be charged e.g. on a laptop while playing music e.g. from a mobile.
I have had to plug mine in from time to time to be able to continue using it as a headset on my laptop.

There is more information on this topic here: https://forum.fairphone.com/t...

yes. you can listen to music while charging the headphones.