I am Makarand P from the Dell Social Media and Communities team.
With regards to your question, you have to navigate to Home on Excel, click on Options>Add Ins and select the AutoPak analysis tool and once done, the Edate option would be available for the cell in which you would have entered. Now highlight multiple cells on which you want the dates to auto-populate and enter the formula as (Cell number(month/date/year) and press enter. Dates should come in with the intervals you choose.
Kindly revert for further clarifications,
Thanks and regards,
Dell Social Media Responder