Until a practice has 8-10 staff there is no real need for an "Office Manager" as what a real OM does is hire, train, apprentice, correct and manage the other staff.
A real OM is not answering the phone, scheduling, doing financial arrangements, etc. However an OM should be able to do all these jobs better than anyone else otherwise how can she properly train, correct and manage the other staff? A vital skill for of an OM is having the expertise to train other staff.
The truth is when you have willing staff who have been trained on proven...