Learn the fretboard backwards and forwards. There's a few online vids that make it a little easier.
This worked for me. Be prepared to spend up to 45 minutes a day. Good luck.
Simple to learn , just don't stop learning , playing , and practicing . Rock on , man
I always say learn on a nylon string guitar before you graduate to a steel string because it will go easier on your fingertips but major chord will come easy to you with the F and B being the only hard ones.
If you mean learning the names of the notes on each fret, it took me about 3 weeks when I started playing (but I worked pretty hard at it). If you mean what you can do with them all, I dunno... I'm 40+ years into it, and I still learn something new just about every day.