Work Order Assignment on creation via the API

Is there any trick to getting the assignments working correctly? I'm running into a dilemma with the assignments part of the ticket. Looking at the docs (http://securecontent.corrigo.com/docs/HelpCE92/html/1c2e2d56-8c37-a470-dd19-f85d3a1b45cb.htm) for the WoAssignment class it says a WorkOrderId is required. The issue I'm coming across is, I won't know the workorder Id until the Work Order is created. I'm trying to have it assigned correctly to start with instead of letting the auto assign to our Call center take over. Any suggestions?