Do I need to find my recovery key if I haven't yet gone to 2-step or 2-factor authentication?

I'm still using single-factor authentication simply because I don't want to run all over the house looking for a 2nd trusted device. I remember setting a key for my account, but can't seem to find it. If I turn on 2-factor authentication (so I can actually see my mail and calendars on a Windows machine), do I need that old key? I understand that turning on 2-factor authentication will make me create a new key.

Thanks.