What is the process to have a pre-emptive database backup ready before a major functional change?

We are planning to have a functional change done to historic data in one of our modules in Oracle Fusion cloud application. Our plan is to test this change in non production environment with a recently refreshed data. Once testing is successful we can promote this to production however as part of the plan we would like to have pre-emptive SaaS database backup ready before the change starts so that if the change doesn't go according to the plan we can restore from the backup.

Please can anyone advise what is the process to request this prod database backup? Do we know how long the restore process will take if the restore is required?