It would be great if Tableau Online had more parity with Tableau Server related to creating schedules.
See the following article for Tableau Server: Create or Modify a Schedule - Tableau
Having this option within Tableau Online, like Tableau Server, would have a number of benefits. It appears that users within Server product are still looking for more options as well, which shows the importance of utilizing custom schedules for refreshes.
Please feel free to reply back with your user thoughts.