Changing Rent Due Dates for Inherited Tenants

[Keith Hand]

I am buying a multifamily property from an older couple who did not manage the property very well. We will inherit roughly 40 tenants. for some reason, the previous owners let the tenants choose their due dates. They pay on all different days of the month. Very few are due on the first, and they are spread all throughout the month. I would like to change all of the due dates to the 1st when we take over. Is this change reasonable, and how do I implement it? We are dealing with low-income tenants, and I am not sure to transition the people who are paying late in the month.