Set up notification of when 100 responses received

Hi everyone,
We have a number of dashboards displaying different cohorts of customer data. We don't want to display data with less than 100 responses to any given question.
We can't do this using the response filter function, as it only applies to each individual response rather than the question as a whole (which is a limitation imo).
I therefore thought about setting up a workflow which would notify my team when 100 responses to a question have been received in a given month, but it appears you can't do this either.
How would you go about doing this? I really want to avoid a situation where colleagues have to go into the data manually to see if a base size has been reached every month.
Thanks
Amy