Yes this is not so easy to solve.
One way would be the approach you already took.
I would modify this a little bit.
Your notification rule should include the tags, the timeperiod and as a new filter “Restrict to n’th to m’th notification”. Now you need to configure that if the host has the tag “daytime_hours” and that there are a rule “Periodic notifications during service problems” is created. If you set this to 10 minutes and you set your notification rule the restrict parameter to “2 - 2” then only a mail after 10minutes is sent.
Pay attention to set the “Restrict to n’th to m’th notification” in other rules to only the first message. 
Here the settings for the notification rule
For normal services
If you want a delay of 20 minutes
