I’ve seen several posts here on this board titled, “Personal Trainers needed in City, State.” That might be a good place to start.
Are you on facebook? Or is someone on your staff on facebook? In my city, there are facebook groups for fitness instructors and personal trainers in the city and surrounding areas. When we’ve had openings at our gym, we post in the local instructor / trainer groups and usually get several inquiries.
Another thing to try is the “find a trainer” part of the home page. Search your zip code and you will notice there are trainers who will pop up locally. Then you have people with whom you can inquire and if they’re not available, they might have colleagues who are.