Hi Leo and welcome to Chordie!
I personally have played rhythm guitar for most of my life... like over thirty years. Mostly because I never took the time to learn properly the theory part of music. Scales, Modes etc. Doing that now, much to late to make money at it.
But you will likely find that if you look through Chordie for those Beatles tunes, you are going to find versions that you can play with mostly open chords, even if you have to capo into another key to make it work. Don't be afraid to try those difficult chords, and learn your barres which are only open chords with your index finger replacing the capo making the chord movable.
Practice a lot and your fingers will learn where to go, do it properly and do it often, and later when you get one of those unusual chords like flatted third augmented fifth add thirteenth you won't wind up tying your fingers in knots.
As to when you are ready? The sooner the better! When you play with others you teach and learn from those you are with. Yeah it is going to take some rehearsals, and you will screw up now and then and have to pick it up again.... usually after we all stop laughing about that wrong chord (what was I thinking there? You sure that wasn't supposed to be G flat Maj 7?).
Have fun with your music, it just keeps getting easier!
Take Care; Doug
"what is this quintessence of dust?" - Shakespeare