I've found many discussions of same day changes searching but do not see it mentioned here https://www.jetblue.com/help/changes...ns-and-standby so I am afraid it may no longer exist.

I am not Mosaic and have an upcoming Blue fare. Am I able to do a confirmed same-day change for $75?

If so, does the window for contacting Jetblue begin at midnight of the day of travel (seems to be mentioned most) or 24h before the original departure (saw a few posts say this)?

And do I need to call Jetblue or can this be done online/in app?

Thank you!