Customizing the Start and End Dates of an SSL Certificate
It is possible to have all of your SSL certificates co-terminating on the same day. This option allows you to set a start date and an end date within the validity period of the certificate. For organizations that wish to dictate a time period, such as a week, in which all certificate renewals must take place, specifying an end date will ensure that administrators commit to this activity. Furthermore, setting a start date allows SSL certificates for future projects to be applied for, paid for, and issued without becoming valid and usable until the chosen start date has been reached.
Note: If you want validity to start at the time of issuance, with only a custom end date, leave the start date field blank and only specify an end date.