A divorce is started by filing and serving a Summons and Petition. By filing, we mean sending these documents to the court files. Service means delivering to your spouse in a formal fashion proscribed by court rules. Once both of these things have been accomplished, you must then wait ninety days until you can get your final divorce.
A divorce is called a "dissolution" in this state. When you file, the clerk will give you a case schedule. This is a listing of events that will happen in your case before you get your final decree and the dates by which they must be accomplished.
You will notice from this case schedule that your trial date (should you progress to trial, and not everybody does) is almost one year away from your filing date. Do not misunderstand what a trial date is. A trial date is the date at which a judge will decide all the issues that remain unresolved in your divorce. It is not the same thing as going before a judge with an agreed divorce decree settling all the issues. The latter you can obtain after ninety days.
The ninety days is intended to provide you with a cooling off period where you can decide whether or not you really do wish to have a divorce.