Your options would be to have more measured time between exections by using Periodically, then setting the time you want. Example of this would be:
This would run every 4 hours after the start time. If you need multiple, exact, unevenly spaced times you'll have to copy the script into another schedule job and configure it the same but with the time you need, one for each time. You may be able to condense these by using periodically whenever possible, but you'd still need multiple.
