What design pattern should I use for WebServices initialization?

I am using SOAP which initialization takes some time so I don't want to this with every request. As far as I know singleton is not proper pattern for this situation. I use static factory method for this which is mentioned in What are static factory methods in Java? Is it good practice?

public class ServiceConnection {
    public static final int MAX_CONNS = 5;

    private static int totalConnections;

    public static Set<Service> serviceIterator = new HashSet<>();

    private ServiceConnection(){
        totalConnections++;
    }

    public static Service getService(){
        if(totalConnections < MAX_CONNS){
            Service service = new Service();
            serviceIterator.add(service);
            return service;
        }else{
            return serviceIterator.iterator().next();
        }
    }
}