Sorry but I am still a littel confused on what you are trying to do exactly.
here are some options that might spark an idea for you or help you to explain further...
If you create a group on the insert date field and set it to 'for each day'
you can do also do an insert summary as a DistinctCOunt of Bill# for each day
and/or
do a time differnece at the group level fromthe minimum date value to the maximum date value to see the time difference on that day
datediff('n',Minimum(insertdate,bill#),Maximum(insertdate,bill#))
Any of this helping?