I have not cruised
DCL, but have with other lines and I have used another cruise message board. The general consensus is that you should book airfare yourself. The transportation coordinator has to book airfare for thousands of people and you may get stuck with either a short connection, long connection or horrible flight times. DCL will book you on the cheapest flights they can which will probably be very inconvienent. You can probably book a flight for cheaper than they can too, unless you are flying from a remote location.
If you are worried about "missing the boat" buy
trip insurance (which is a good idea for cruising anyway, esp for medical evac).