I don't think it necessary to be able to read music before picking up a guitar, but it may be helpful, as may a quick grasp of Tablature.

I find that the "classroom" and "practical" side of playing go together. When playing along to another instrument, it is useful to know the chords for a given key, and the relative minor; then for more advanced play, learn things like the pentatonic scales and so on.

I am well aware that some playing and composing geniuses manage without any theoretical knowledge, but lesser mortals like myself can comprehend better what I am trying to achieve, if there is at least some sort of logical system underlying it.

By the way, in my long-distant youth, I learned a lot of theoretical stuff for the piano, which has proved almost useless for the guitar. I still cannot relate a position on the stave to a string and fret on the guitar; which is why I suggest that Tab is a good skill to have.