CH ... the previous posts highlight the challenge to be faced. As a new entrant WSO, you have a clean sheet, broadly speaking. As a WSOp seeking commissioning, the Board will have reams of data on you which may, or not, be to your advantage.
There is NO advantage to be gained from starting on a low branch of the tree when you can instantly jump several branches higher and start as a WSO. You would just be wasting time, seniority and money. If you're deemed suitable for a commission as a WSO ... just bloody GO FOR IT!