Eventually. My dd and I are flying JB out of Boston to MCO in early Dec. We are on two different reservations since I booked my flight about 3 months prior to booking dd's. It's been interesting to see how they handle changes. There have been times when I get an email/phone call alerting me to a change in dd's reservation, but I get nothing for my reservation. Other times, I get notified about my reservation but nothing for DD. They aren't tied together...so are treated as such, two different reservations.
Jetblue does let you know in advance. But, there can be last minute changes. My dh and dd were flying down to join me. They had a 3pm flight out of Boston. Dh is obsessive about checking on flight status, so checked it just before they left the house for the airport. He checked at noon and it was ontime, do did online checkin. By the time they got to Logan, at 12:45, the flight had been cancelled!!!! They were lucky enough to be put on the 1:00 that was just getting ready to close the doors....ran to the plane, sat down and off they went. They had to get on that flight since they had a connecting flight in NY...if they had taken the flight the other 3:00 flight passengers were being put on, they would have missed that connection and been stuck in NY overnight.
So...there can be last minute changes.