On February 25th, 2022 Valve will begin sending out emails to reservation holders in the order that reservations were made. You will have 72 hours from the receipt of your email to make the purchase of your steam deck. If you do not purchase your reserved Steam Deck in the 72 hours, the reservation is released to the next person in line.
Units will start mailing on the 28th, and Valve plans to continue sending new emails to reservation holders on a weekly basis.
Invites will start after 10:00 am PST on February 25th, so set your alarms if you anticipate being in the first round!