One trick -I didn't tried but maybe works- can be setting a document that loads hourly with condition to throw an error outside the desired reload periods. Any non-existant sentence will thrown an error, like "ThrowError"
The main document loads when this document has a successful load.
Or directly set this conditions on the first tab of the document, so it only continues to load on desired time periods.
Another (cleaner, but harder if you don't know it) way can be using EDX: