Seat reservation before the first day of usage

Hello JR Pass Team!

Is it possible to reserve seats before the first day of using JR Pass?
We arrive in Japan April, 22 and exchange the Order for the JR Pass the same date but start using it only a few days later (presumably, April, 26). Can we make seat reservations as soon as we get the Pass ( April, 22) but before the date of the first trip (April, 26)?

Best regards,
__
Vera