How to deactivate notification on iPhone during an important Phone call

Hello,

I have an iPhone and I would like to know how to prevent sound notifications (email, text messages, phone calls...) during a phonecall.

I know there is a mode called 'Do Not Disturb', is that the best way to do this? Can I activate that mode before the phone call?

Ideally I would like to be able to turn on the appropriate mode one hour before the phone call but I would need to be sure that the desired phone call will not get filtered and that the phone will actually ring when the person will call me.

Also, is it possible to select which application gets allowed and which application gets filtered using that mode or not?

Thank you very much for your help.

Regards!