Please use $date.NOW() (where $date is date.js) instead so unit tests can have an easier time of this.

Also, I think we probably want a comment along these lines:
// Weird things can happen if the device's clock goes back in time, but this way, at least the user can change their default if they cycle through their accounts.

Specifically, I don't think it's worth adding complicated logic to support this unless you think we should do Math.max(Math.max(known priorities) + 1, $date.NOW()).