It is recommended that you and reviewee meet as soon as possible after the observation to discuss feedback. Again this could potentially be done over a cup of coffee.
You will then provide the reviewee with written feedback targeting the agreed areas within two weeks of the observation.
What were the benefits for you the reviewer?
As a result of the Peer observation experience you may wish to consider the following questions:
An action plan template may assist this process. See Peer Reviewee Reflection Sheet (doc)