One of the best ways to establish trust with your patient is to stay in communication with them. First of all, you do want to verify their preferred method of contact, as this may vary from their demographic screen and they may prefer a different method to know when their glasses will be ready for pickup. 

Also, set achievable expectations for when their glasses will be ready. 

And third, if there happened to be any delays in regards to their order, you do want to be the one to contact your patient, not the other way around.