JR Ticket Vending Machines at HND Terminal 3

Are JR East ticket vending machines at Haneda airport Terminal 3 open 24 hours?

No, both the ticket machines and the Travel Center ticket offices are open only between 6:45 and 20:00

How about the ticket vending machines at Tokyo station? Are they open 24 hours? I am planning to leave Haneda airport or Tokyo station as early as possible in the morning to get to Nagano.

you can buy a ticket just before you ride on the train.
no one will come to train stations when no trains are running. (the station gates are closed.)
for example, when you want to take a train departing from 5:00AM, I am sure you can buy a ticket at 4:45AM at the station.

Actually the earliest Shinkansen from Tokyo to Nagano departs at 6:16. To catch this you may need to get on 5:26 Keikyu (transfer at Shinagawa) or 5:27 Monorail at Haneda airport No.3 station (transfer at Hamamatsucho. As ken said if the train is running you can buy ticket on site.

Thank you all for the information.

Just fyi, I will be arriving at Haneda airport midnight and overnight there for a few hours before getting on trains to Nagano.

I am planning to get JR East pass (Nagano, Niigata) for my trip and in a thought of at what earliest time I can get the physical pass if I purchase it online.

Just fyi, I will be arriving at Haneda airport midnight and overnight there for a few hours before getting on trains to Nagano.

You should have written this down first.

I am planning to get JR East pass (Nagano, Niigata) for my trip and in a thought of at what earliest time I can get the physical pass if I purchase it online.

Pick up your pass.

https://www.jreast.co.jp/multi/en/pass/purchase.html

https://www.jreast.co.jp/e/downloads/pdf/passport_operation_e.pdf

I think you can pick up your JR East Nagano Niigata pass at Haneda Airport Terminal 3 after 6:45.

Haneda Airport Terminal 3 Tickets *Open 6:45 - 20:00

Or you can buy ticket(s) to Hamamatsucho or Tokyo and pickup the pass there.

As far as I understand, the earliest time you can get the pass is 6:00 at Haneda Aiiport Terminal 2 station
Tourist Information Center (manned counter).

https://www.jreast.co.jp/multi/en/pass/purchase.html

https://www.jreast.co.jp/multi/ticketwindow/

Tourist Information Center Haneda Airport Terminal 2
Hours of Operation
Purchase 9:00-21:00
Exchange: 6:00-22:00

How to get from Terminal 3 to Terminal 2.

https://tokyo-haneda.com/en/access/travel_between_terminals/index.html

What is the earliest time for me to pick up pass at Hamamatsucho or Tokyo station?

It seems both Hamamatsucho and Tokyo stations have gTicket vending machines with Passport Readerh

https://www.jreast.co.jp/e/downloads/pdf/passport_operation_e.pdf

If you can use these machines, you can pick up the pass after 5:00 if I read the JR east page correctly.

Ticket vending machines
with Passport Reader
JR-EAST Train Reservation tickets and passes can be picked up from 5:00 AM to 11:30 PM.
*Hours vary by individual pickup location.

Note that I am not a staff of JR East so I can't gualantee the correctness of the information.

Thank you for the information. It helps me a lot.