I would have a follow-up conversation (in person & in writing).Restate the rent due date, Let them know if they are late, the date they will get a notice, and let them know when an eviction notice will be sent in.I would also start trying to automate if you don't already via PM software -  It will automatically send a rent-due notice a couple of days before the actual date it is due, then again the day it is due, and then if they are late.

John, the company I have worked with has an automated service that reports to all three credit bureaus for 7 years.

The second things become automated I will wind up with prom groups and bachelor parties and things I filter out currently and my house will wind up trashed.  

So if an owner has an issue (water heater breaks, etc) they know who they are dealing with, I know local contractors, etc and no one ever gets put on hold to listen to elevator music or asked to press 30 automated phone selections to get to a live person.

At this point you can simple put all your focus on acquiring properties, growing your business and implementing additional techniques for automation. 

You could always consider doing it yourself for 6 months, then get the automated program to see if it's actually providing you better results.

Automate all kinds of things.

You can automate check in.

The calendar software i used either automatically sent to Airbnb guests or sent me a push notification to manually send to guests through Vrbo (I believe these messages can now be automated, but I am taking a break from hosting and I’m not quite sure)

Connects to most major channels and allows for a lot of automated messaging.