Another question:
When you order a new aircraft when it will be delivered? Exactly after one month or at the time when the current month changed into the next month?
Aircraft are delivered on the first of the month. Delivery was initially the first 20 aircraft + 20% of the current orders. Last round or so, it was changed to the first 30 aircraft and 20% of the order book. However, each airline can only receive 2 aircraft per manufacturer at a time. So, if your aircraft is #40 in line and all the orders in front of you are from the same airline, you will get delivered at month change.