Appendix C to Regulation CC contains Model Availability Policy Disclosures. There is no model form for same-day availability. You may want to ask the examiner for a source of the information that he/she sent you in search of. I suggest modifying an existing form, such as the next day availability form, to make it work in your situation. In doing so stick as closely as possible to the existing model language.
Add I encourage any other users of the Forum to respond if you have had a similar experience.