Basic level guitar player, Wanting to learn music theory to understand and create on my own

[Chrisguitar]

I have been playing guitar for a year or so, Am I a four chords guy, Know some barre chords too, But have no idea of scales, Progressions, Note placements on fretboards. Recently started watching videos and trying to understand music theory. Can someone give a roadmap of how to learn things the right way?? I'm using YouTube as my source, Don't have dedicated time for guitar classes. How long can it take before I get a decent grasp of how things work in a song? And don't have to watch tutorials to find chords of a song?