Renter wants to line up his rent payment with his check..?

[Chantz Ireland]

I just bought a Triplex and am now about to collect rent for October. Last month the renters in unit 1 were late. I bought the building from my father and he said that they are late every month and usually don't pay tell around the 10th. This doesn't work for me and would like to figure out how to get them to pay on time every month. 

I texted the renter 4 days ago and reminded him that rent was due on the first. I woke up this morning to a text saying that 2/3 of them occupying the unit don't get paid tell the 9th and will be making there payment then. 

Do I start charging him late fees or let it slide..?  Any ideas would be extremely helpful.