You can get the date of the earliest release in the release group using the originaldate and originalyear tags in https://picard.musicbrainz.org/docs/tags/.
To get the earliest date for an individual recording, I think you’d have to develop a plugin to look up each release associated with the recording and select the earliest date. This would have to be done for each track that you’re tagging. Unless I’m missing something, this does not appear to be a trivial exercise.
I know this isn’t what you wanted to hear. There are a lot of talented code / script writers here, so perhaps someone else has a better suggestion that I missed.