Dangerous and risky words, "Let's work together for six months or a year, and if we decide we still want to go through with it, we can complete the sale at some later time." If you want to doom the transition to failure, then just try using the trial period approach to a practice transition.
The request for a "trial period" is a way of holding back a commitment, and you can rest assured that the results will be less than satisfying. A commitment from both parties is what is needed to make a successful transition.
The practice transition process is complicated but it can be successful. After the necessary interview process and addressing the "what if's" get your agreement in writing before the new dentist even picks up a handpiece! The main thing is if both parties are comfortable with each other, then that is usually all that is needed to make it work.