It might be on useful to think about the relative importance of musical notation for a beginner.
Playing a musical instrument involves a wide range of capabilities. Reading music (in whatever form) is just one of them, and an optional one for many people. When we are just getting started, it can be frustrating trying to decide what aspect of music to work on first. I have long and extensive experience as a musical performer. I can read many different forms of musical notation. But when I started to learn to play a new instrument—a free reed instrument, musical notation was the last thing on my mind.
To learn to play well, I would have to master the techniques that produce the sounds that attracted me to the instrument. I would need to play long even notes, and long notes that gradually got louder or softer. I would need to be able to play legato (making a smooth, connected transition from one note to the other), and staccato (short, unconnected notes). I would need to learn to manage the flow of air, and so on. To do those things, I needed to teach my fingers and hands (and brain) new, unfamiliar movements. Some fingers were better at it than others. What could I do to make them as equal/capable as possible? What the names of the notes were or how to write or read the melody of a song were and would be irrelevant until and unless I could make the necessary sounds. Notation was a concern (and there are a couple of concerns) for a later time.
It is commonly said that you need to spend 10,000 hours to master something as complex as playing a musical instrument. Let's say that you don't want to master the concertina, but just play at the level of the lowest 10 percent of players. You will have about 1,000 hours of practice ahead of you. How should you use that time? It is very common for beginners to attempt to play simple songs. I didn't do that. It was months before I worked on any actual music. Even now, seven years later, very little of my practicing involves playing thought entire pieces. I practice the hard parts of things I am working. I also practice the ongoing skills I need as I get better.
Performers at the highest level emphasize the importance of learning to play without any tension. They emphasize the importance of practicing slowly (since playing fast is nothing more than playing slowly fast). They emphasize the importance of listening carefully to the sounds you are making. The emphasize the importance of isolating and practicing the things you find difficult slowly and relaxed enough that your muscles can learn how to do whatever it is. Too often, people play/practice too fast, making the same mistakes over and over, essentially practicing and getting very good at making the mistake.
We all have big hopes for making wonderful music. Fortunately, even on day number one you can begin to practice some little aspects of that. Figure out a couple of the notes. Play them slowly and relaxed. Listen carefully to make sure you like the way it sounds. If you can't make it sound the way you want it too, figure out what you need to solve that. That is what practicing is. You don't need any musical notation to do that.
I hope some part of is helpful.