I think you slightly overcomplicate string muting. It's very easy and you can start doing it at any point, even if you are a complete beginner.

You can mute strings either with your right or left hand. Doing it with the right hand (playing hand) is called palm muting, since you are using your palm to mute all the unnecessary strings.

Something that is mentioned not so often is muting with your fretting hand. This also often is necessary to do.

Sometimes I use my thumb to mute 6th or 5th string, for example when playing A or D chords.

Other than that you can mute a string by plucking it with your index finger. This is particularly useful when playing solos.

There is no specific point when you should or shouldn't start using string muting. It's just a technique that allows you add cleanness to your playing and thus make you a better guitar player overall.

I highly suggest you to check out the guide, where I mention all the basics that beginner guitar players should get familiar with.[br][br]https://beginnerguitar.pro/how-to-improvise-on-guitar-guide[br][br]If you have any questions - let me know.