I know I have to give the tenants 60-days notice to vacate but if they do not leave do I have to go through a costly court process?  

I would love to get to know the flipping side of the business and I would be more than willing to help out any active investors in any way I can during my off time from work so I can familiarize myself with the business/processes of flipping houses.

Aside from predicting the future, how can I change my process so that these letters come in a more timely fashion?

It is better for them to get half the profits than no profits, and you gain invaluable experience as they take you through the process with them.DO NOT go half-cocked and mail without having an understanding of the legal requirements for your area for assignment contracts.

Let me know if you have any questions about the process!

You are going to learn more by implementing the process than anything else.The most important thing is understanding timing of a wholesaling transaction and writing the contract correctly.

How far along we're you in the process ?

If you get a certificate, your exit strategy is one of two, either you wait to have it paid back to you, or you wait until the specified time period has elapsed, and you get it perfected by the taxing entity (that process varies).

(They are already arguing over who its entitled too) I'm just hoping to come to an agreement that doesn't end with an expensive eviction process or serious property damage...

They can help you navigate through the process and inform you of all your options.