Another thing I want to add. I urge you to first experience your VA business and learn what it's like to deal with clients and provide services for them before you start sub-contracting out work.

In the corporate world it would be very unusual to place a new project manager in a role who has absolutely no experience in that particular industry. You need to think about this very carefully. Until you have experience of running a VA business and dealing with clients, my own personal opinion is that you wouldn't yet be eligible to project manage a multi-VA practice - unless you have considerable experience in something similar.