I think (this may not be the case) you can get more than one aircraft in a day if you buy them not lease them.
Buying aircrafts shows the same delivery schedule as leasing them, so I don't see how to get more aircrafts in one day:
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Deferring the order gives you about 13 options, but in this picture the airline has ordered about 20 that are showing in the screenshot and another 100 that didn't fit on the picture. All to be delivered on May 2nd.