Fifteen minutes.
DEVICES
Are updates applying on every device? Is anything running an unsupported version?
BACKUPS
Did they run? Do they include what you expect?
ACCOUNTS
Any login notifications you did not trigger? Any new accounts on your systems? Any mail rules or forwarding you did not create?
MONEY
Bank transactions reconciled against your records Any unexpected payees or payments
ALERTS
Anything from security software or services, acted on rather than dismissed
WEBSITE
Loads correctly, certificate valid, nothing unexpected added
PEOPLE
Anyone left this month whose access has not been removed?
WHAT TO RECORD
That it was done, and anything found.
WHAT TO DO WITH ANYTHING UNEXPLAINED
Investigate before dismissing.
WHO DOES IT
Someone specific, on a set date.