You are running into a rare situation. Likely what's happening is that we cannot acquire the instance type you chose for the job cluster in time and you're hitting an optimization where we go ahead and start your job anyway with the workers we could acquire, and add additional nodes as they arrive. My recommendation is to configure a cluster with a different instance type and a smaller number of nodes.

By the way, why do you want the job to only start when all the workers are available?