It's wonderful to be able to teach something that I enjoy much, every student is different and it's always about simplifying, encouraging, understanding the student and moving from what we know to discovering a whole new world within music.
To learn basics would need 3 weeks, introduction to guitar, familiarity with string, fret board, strumming, forming chords, playing and singing.
Learning scales will require some time of practice, 3 weeks, will open up a while world of possibilities, understand how people play.
There is no beginners age to learn music, if you can apply yourself, you can learn, I say because I have taught 70 year olds, who were enthusiastic about the new skill.
Teaching school, college students, office going people who wish to learn guitar and start off on a new journey discovering, chords, scales the language of music in theory and applying all the theory appropriately on time to stay musical.