Just a quick possibility here... As far as I'm aware, there are only negative effects of scheduling your routes onto airplanes that have yet to be delivered (~2 weeks or less). You need to pay for the extra staff members for example, even though the route is not flying. Maybe a trade-off to the negatives would be that the RI starts climbing as if you're already flying the route as soon as you schedule it to an airplane that has yet to be delivered. This would simulate the route being "in the system" and your passengers would be aware of the route and be able to book a ticket in advance of the route actually being flown. Make sense?