So far, I have reservations in the system today for 6 of my SWUs... two trans-atlantic (Brussels next week and Zurich in June) and one trans-pacific (Beijing in May). By talking with an agent in advance of booking the ticket (my reservations have to be made by corporate travel), I have selected days and routings that have Z availability. I never had to change my departure/return dates by more than +/- 1 day to find Z availability. I am in the situation described above where any booking in Business is not allowed by the corporate travel policy but a YBM booking is OK.