I'm a largely self-taught jazz guitarist playing at a very advanced amateur level (light giging, I host a jazz jam), so I can speak with some authority.
Depends what skills you bring to the table.
For improvising:
The Jazz Theory Book -- Mark Levine
The bible for jazz students. Assumes an ability to read music on standard clef, and assumes that you will find an alternate source to teach you the scales that get applied in The Jazz Theory Book (which is instrument-agnostic).
Prerequisites:
Some ability to read treble clef. Enough familiarity with jazz cords (e.g. G13, D7b9, Em7b5) to play them or know how to construct them. Levine will take you through the chords and matching theory, but (because it's instrument agnostic) won't teach you how to play the chord.
Syllabus: start at the beginning. For each mode covered in the text, learn the mode in all five positions; learn to hear it and apply it against the musical samples that Levine gives in the sidebars. This means that you'll progress at a rate of about 2 or 3 pages a week for quite some time. It would be a good idea to purchase a Real Book, and learn the complete tunes for the examples that levine gives. Work completely through the transcriptions levine provides (a couple of weeks for each). Expect to spend at least a year to work through levine the first time, and expect to do the entire book cover-to-cover at least twice in order to really absorb it.
If your reading is weak, learn to read directly from treble clef. Do NOT transcribe through tab. It may be slow going at first, but this is not an optional skill.
Time spent with a teacher at this phase would be time well spent. A couple of months of lessons could save you years of study by setting you on the right path early. That being said, my personal experience is that full-time teachers aren't productive. My path has been: study intensively for a while; go to a teacher to get fed new material that will take me months to master; repeat. Don't waste your time with guitar teachers that don't play jazz for a living. Posers are common, and are not useful. Lessons from a pro jazz player don't cost significantly more than lessons from a poser.