To link your reservation to
MDE, you will need the get the Disney Reservation number. It is a 12 digit number that starts with a 4. You should be able to get JetBlue to provide it. Worst case would be that you could call Disney Central Reservations and have the agent look up your reservation by searching for you name based on the dates of your travel.
The Magic Band question was 99.99% answered by Robo, note you might not get them until you arrive at your Disney resort in a worst case situation.
Just make sure to the Disney Confirmation number and link it to your MDE and you should be able to customize your Magic Bands and have them shipped to you. This assumes that you are in the US or a location where Disney will ship them. Make sure that your reservation is linked in MDE and then you should see the option to customize your Magic Bands.
How far away is your vacation as this affects that ability for Disney to customize your Magic Bands and ship them to you?
Dave