Currently we sign timestamp every three days with expiry in 7 days. We have our tests set up to file an issue if timestamp goes invalid in three days (7-3 with one day buffer). On-call uses the same test with a two day trigger

#1339 will now change singing to happen every day.

plan after the signing event:

• we can set our test to file an issue if timestamp goes invalid in five days (7-1 with one day buffer).
• on-call alert could be set to trigger at 4 days

This can be done in root-signing-staging first