Technically you should be able to, but when I went to book it, the month of May was not in the system and neither was the SoA that I was trying to book (told me that May will be loaded soon, so try back each day). However, it was during the time when the whole system was being updated, so I am guessing you should not have a problem with yours. You can also book that online now, which is part of the new system upgrade.