WA CA 7 Edition
CA 7 has nothing to do with TIMEZONE command. CA 7 will use the local time and it get the time from job starts/ends from the SMF records.
It is possible that the end time can be before the start time if the time changes while the job is running.
As for the SSCAN, there are no problems. CA 7 knows what has already been schedule and changing the time will not affect it.