Anyone changed arrival date after medication permit approval? (Vyvanse / Elvanse)

Hey, has anyone here gone through the process of applying for permission to bring Elvanse/Vyvanse into Japan?

I already sent my application, but I’m wondering: once it’s approved, can you change your arrival date—especially if you want to come earlier than the date you originally put down?

Would love to hear if anyone’s had experience with this and how flexible the process is.

Thanks!