COVID-19 Disclaimer: Please understand that the information given here represents my knowledge and experience from 2019. Due to the worldwide pandemic which has largely influenced the situation in California you may have to do more own research how it may work in 2020.
So you want to hike the JMT? – But before you can go you must reach it. And after your adventure you want safely return home.
The JMT is not a round trail – you end some 300 km away from where you started. Those groups of hikers who have two cars available simply place one on one end, and the second on the other, and have their transport solved. Not for us – we do not have even one car, or do you want to pay a rental car for 2, 3 or 4 weeks standing in a parking lot?
So you either need to rent quite expensive shuttle services, or try to make the best out of a public transport system which is nearly non-existing, according to European standards. First rule: avoid weekends. The ESTA (Eastern Sierra Transit Authority) bus line operates only Monday to Friday. Car rental stations are closed on Saturday afternoon and Sunday, same for the post office. And at least in Yosemite valley you will for sure try to avoid the even bigger herds of day visitors on Saturday and Sunday.
I recommend a start between Tuesday and Friday. Adjust your travel accordingly. You should finish the hike on Friday noon at latest, Thursday would be better. Check all the timetables and opening hours and plan everything before you start to buy the first ticket.
As an international traveller, fly to LA or Las Vegas. Even if the flight to SF may have the same or an even lower price, everything else, e. g. accommodation and car rental, is more expensive. Remember that you need to rent your car one-way, and try to find a company and route where you are not charged extra.
My approach for pre-hike:
I fly to LA and arrive Friday afternoon. I rent a car for three days from LAX to Bishop from Enterprise. Then I drive to the motel and go to bed early.
On Saturday morning I go to the post office where I claim packets sent to me at general delivery with gear like the bear can. After that I visit a WalMart, a hardware store and possibly other shops. I prepare the resupply buckets to VVR and Red’s Meadow and mail them.
On Sunday I vist the local REI to buy some last gear items which are better available or cheaper than in Europe. Around noon I start my travel to the East Sierra valley until the Onion valley campground where I deposit my first resupply bucket in the bear box at the parking lot. Then I may have dinner in Independence and stay the night perhaps at the campground. Variations possible.
On Monday morning I drive to Bishop to return the car. I have packed all the stuff which I do not want to carry on the hike in a packet which I now sent to myself, Fresno post office, general delivery, and one set of clothes to Tuolumne Meadows post office. I take the ESTA bus (yellow line) leaving 1:15 pm for Lone Pine. After arrival I go to the Eastern Sierra Visitor Center to pick up my permit. Then I use Lone Pine Kurt’s shuttle service for the horseshoe meadow campground, if possible share the cost with other hikers. And there I am, ready for a start the next morning!
My approach for post-hike:
25 days later I arrive at Yosemite valley latest at Friday noon. If possible I shower and change clothes against a fresh set which I have claimed from the Tuolumne Meadows post office two days earlier. I then take the YARTS bus to Fresno (run 23) leaving at 4 pm and arriving at 8 pm. I check into the motel and enjoy a dinner.
If something goes wrong I can use the run 25 of the same line 1:40 h later.
The next morning I go to the car rental station and fetch my car, then to the post office to claim the packet with extra clothes and other stuff waiting there for me, and return the rented bear can. I drive back to LA where I may arrive in the early afternoon. I check in at the B&B and still have the evening to enjoy. The next morning I drive to LAX, return the car and prepare for the flight home.
Update after the hike:
Most tasks worked as planned and expected.
Changes: I found out that LAX PO has no general delivery service, nor any PO in Fresno that is open on Saturday, so I sent my unused stuff to the B&B in LA. I skipped the Tuolomne Meadows PO and put my set of post-trail clothes into the Red’s Meadow resupply. I claimed the permit already on Sunday but shipped the resupply packets only on Monday from Bishop. I did not rent a bear can but bought my own BV500 during Independence Day sale to save some time.