You can purchase a Japan Rail (JR) Pass up to 90 days (3 months) before you plan to exchange it in Japan. When you buy the pass online or from a travel agent, you receive an "Exchange Order" (voucher). This voucher is valid for exactly three months from the date of issue. Once you arrive in Japan, you take this voucher to a JR Exchange Office to receive the actual physical or digital pass and set your official "start date." It is important not to buy it too early (e.g., 5 months before your trip), as the voucher will expire before you arrive. However, in 2026, some official vendors allow you to "pre-order" much earlier; they will simply hold your order and only issue the voucher once you are within the 30-day window of your departure to ensure its validity.