Ideally you would want to take as much time as you need to complete you divorce.  There are so many areas of your life that are impacted, and will be impacted so it is not something you want to be rushed into, or rushed through. 

You can start the divorce mediation at any time during your divorce, however if you have already filed for divorce then a clock has started ticking due to deadlines and statistical goals that the courts have when it comes to divorce.