PostgreSQL: restore a database after an incident and measure the RTO

It is 6 a.m., the payments database will not come back up and the CTO asks you one thing only: how long until the service is back. You have the encrypted backups uploaded to S3 the day before and a blank standby server. This scenario follows on from the previous lab's backup chain, but on the side that really matters: the restore. You fetch the archive, decrypt it, bring the database back on the standby server, switch the application traffic back and put a figure on the whole thing, in a time you measure. The sandbox starts with the incident already under way: the main database is corrupted, the backups are in place, the clock is running.