There is always a bottleneck in every single business.
Here are the stages:
1. First it is customers.
If you already have the ability to provide the service yourself, you just need a customer or two to get the ball rolling.
As soon as you get those first few customers, you have a business and you are off to the races.
2. Employees.
Next, once you have enough customers coming in the door where you can no longer do the work by yourself, you need employees who can provide the service on your behalf.
At this stage, customers pay you, and your employees execute while you oversee them.
As the owner, you still do most or all of the admin work yourself.