what is the impact of changing log shipping schedule timing jobs?
As Shanky noted, this is not a problem as long as you are not actively conflicting with your own SLAs around backup/restores.

The documentation notes you can customize the jobs as needed (steps #8, 16, 21):


  Note the backup schedule listed in the Schedule box under Backup job. If you want to customize the schedule for your installation, then click Schedule and adjust the SQL Server Agent schedule as needed.