I disagree. Most states have mandatory grace periods. Even in Wyoming, which has few tenant - landlord laws, we are required to give tenants a 3-day grace period. The landlord can extend this grace period, but not shorten it. So if rent is due on the first, I have to give the tenant an additional three days to pay, which gives them until the fourth of each month. This is extended if the first of the month falls on a holiday or weekend.
You need to do three things:
1. Learn your state and local laws before you do anything about a late payment.
2. Slap yourself for not having a lease agreement.
3. Create a lease agreement!