I have a sub with extreme anxiety who also has a similar worry. I always send him multiple emails before our session date, just saying something along the lines of "can't wait to see you on X at X time!" etc just to help reassure him.

But I only do this because he communicated to me that he has this anxiety. I think if you told the person you were scheduling with about your anxiety around this, they, hopefully, would do something similar to accommodate.