Sequential Formula for months based on a 4, 4, 5 schedule

Hi,

I am looking to put a formula (which will be ultimately nested within a larger formula for a lookup) that tracks the life of a Cohort. In the attached file, Row 1 are listed Cohorts and the month the Cohort is in each week. Since months are 4.33 weeks, I want the third month of the quarter to assume 5 weeks and all other months 4 weeks.

Cohort 02/01/2016's 52nd week would be in January 2017. Also I don't have any values past 12/1/2020, so once that time passes .. just cycle through the 2020 months again.

Thanks in advance for the help!