The entire mutual consent divorce procedure starting from the date of filing till the passing of the divorce decree can take around 6 months to 1-1.5 years at the most. This period of 6-18 months is exclusive of the waiting period to file for divorce.
The Supreme Court in Anil Kumar Jain v. Maya Jain, has also held that the period of six months between filing a petition of divorce by mutual consent under Section 13-B(1) and grant of decree of divorce under Section 13-B(2) of the 1955 Act cannot be waived off by the parties or by any civil court or High Court.
However, in Amardeep Singh v. Harveen Kaur, the abovementioned cooling-off period of six months has been held to be directory and not mandatory.
I hope I was able to clear your queries.