Don't cancel a lease, that is trowing away money. The plane will make money afterall, perhaps not as much. Fleet commonality is always overrated, especially in the start of a world. Take a good route, there must be enough with not all demand met! If you need many planes in a hurry go outside the box. Chinese and Russions kick ass in availibility and low lease prizes just don't use them to long (maintenance costs). You will make more money with 30 Tupulevs than the 5 737 you can lease in the same time!