I’m not sure I follow your schedule and such, but if you have a 19-day window “now”, I’d just hike WA (or as much of it as you can manage), and take a bus to Medford for when you need to be there. Why bother “training”? you can’t really train much for a long hike like this… so long as you’re in decent shape, that’s good enough. Whatever you do, the first bit will probably be a bit painful, but that goes away…
anyway, sorry I can’t be more specific, but any part of the PCT will beat a day in town :-).
Another option for an early autumn hike might be the Oregon coast trail… but that’s a different kind of experience, and maybe not what you’re looking for? you could always use that as a backup… I mean, plan on the PCT, but if the weather deteriorates, just bail and do “plan B”. Pretty much anywhere on the PCT, you can hike “out” in a day or so, and be in town. Good luck out there!
jonathan