SATOP is always required to reinstate your license if it was suspended for blowing over the limit, or revoked for refusing to blow. It is sometimes required as part of a plea bargain agreement, and can also be court-ordered by a judge. If you lose your license for blowing over or for refusing, SATOP must be completed prior to reinstating your license. So long as it is completed AFTER the arrest, it will count for the purpose of any requisite for license issues.
If you are ordered to do SATOP as part of a plea bargain agreement, or are ordered to do it by a judge, you will have a set amount of time (often times 60-90 days) to complete the program.