Which is ok asthe people you know would understand that you are that type of person.

I would also pop up when someone reinstalled the app.

Would be rather annoying but it should be on as default and the first time it pop up give clear information.

Whatsapp is set to notify you when a key changes, this could be due to a change of phone or reinstalling the app. If you do not wish to receive these notifications click here.

Which would allow users who want it to keep and those that don't to turn it off after the first change.