From my experience this is your CA's fault, and you should get a new one. My CA could tell me at any time how many slots she had left for which production month.

For example when I first contacted her and told her my requirements based on lease end, she could tell me "OK I have 7 slots for July production 35i, 4 slots for July production 50i, 2 slots for July production 35d". Those obviously changed over time and I told her to even keep me posted when there were 2 or less slots available for 35i July build and she did.

Based on what she told me, she had real-time access to this and when their dealer entered the order, the available slots immediately dropped and the order number is issued shortly thereafter when the order is confirmed by SC.