Custom Time Scale - Calendar Month Mapping

Hi All,

 My model Calendar is 4-4-5. So Dec 30-12-2019 is falling on Jan Month. I want to get Jan month 31 days, Feb - 29( and Feb 2021-28 days), march -31 days,apr -30 days..and so on. The Model calendar follows 4-4-5 Total number of months is not giving the right answer.