Date/time filter on nested items

I'm trying to figure out how to do a query to find businesses that are open
at a certain time in the day. For each business I have a nested list of
"hours" that each contain the open and close hour for one day of the week.

I've put a simplified curl log at https://gist.github.com/3192015

In that example, one business starts at 9AM, the other starts at 7AM one
day and 8AM the other. My search attempts to filter it down to businesses
with a start time before or at 8AM. However, both clinics are being
returned.

Is this the right way to be trying this? Is there a better way?

Thanks,
-Thomas