There are two (2) answers to that question:
1. If the parties agree on a no-fault (irreconcilable differences) divorce, then there is a mandatory 60 day waiting period from the date of the filing of the divorce petition before the divorce can be finalized. Remember, the 60 day time period time does not start running until the Divorce Petition is actually filed. During that time the parties have to complete and file a "Property Settlement Agreement" which settles all of the property rights between them, and, more importantly, provides for the care, custody and control of any minor children. This type of uncontested divorce requires the complete agreement of both parties; it cannot go forward without that. This type takes around 90 days from start to finish to complete.
2. If one of the parties proceeds with a "fault" divorce, then the other party has to be served with a summons and the divorce complaint. He or she then has 30 days to file a response or object and, if that is not done, the divorce can proceed as "uncontested." This generally takes around 45-60 days from start to finish if there is no objection from the other party. A "Property Settlement Agreement" is not necessary and you don't need both parties to agree.