New Investor question about tenants & paying rent on time.

[James H.]

Hi I purchased a triplex in a decent area with inherited tenants. I closed a few days ago and I went to the property to hand out a welcome packet. This included a welcome letter stating all the normal stuff, I informed them that rent is Due on the 1st and late on the second. I gave them all of the details they will need going forward. I included a brief form that I asked them to fill out and email back to me. They all did this promptly. One tenant wrote me to tell me that they are on disability and their check doesn't come until the 3rd of the month and that's when they can pay. The second tenant uses his social security and told me gets that check on the 3rd Tuesday of every month and that's when he can pay. 

Tenant's were inherited, all of them smoke but not in the units. Units are well kept and clean. One tenant is on a month to month lease and the other is finishing a one year lease in May. 

Both tenants pay virtually all of their own expenses and rent is low on both by perhaps $100-175 

I want them to pay on the 1st. What can I say? Can I get into trouble for demanding 1st of the month? I wan't to treat this like a business from the very start. 

What should I do?