Hi,
The archive feature does not allow you to specify a precise time to back up the configuration. You can only specify a time period in minutes for regular configuration backups. Your momentary configuration creates a backup only when the configuration is locally stored using either write memory or copy running-config startup-config commands. If you want your configuration to be saved in regular intervals automatically, you need to add the time-period minutes command to your archive configuration.
Would this solution be sufficient for you? If not, there is perhaps an option of setting up a tool called Kron to do these backups periodically outside the archive feature.
Best regards,
Peter