I have not seen my old friend in a month of Sundays.
month of Sundays
idiomA very long time; a period regarded as too long.
Origin
disputed originProbably a reference to the passing of as many Sundays as there are days in a month, that is, between 28 and 31 weeks.
The car has been sitting in the garage for a month of Sundays, so it will not start.
Having spent a month of Sundays waiting for the project to finish, the team finally grew impatient with the constant delays.