Basically we want 3 things:

1. Query terms and get their date of first appearance in docs
2. Query terms and get their date of first appearance AFTER some date (and also the distance between term's date and that fixed date)
3. Query terms for a time slice and compare with previous time slices

Also, think about adding the date to the terms table (but keep in mind the performance of the query).

Also, if we don't want to overload the terms query, we can put that in a Board node instead, with trending terms, in a widget.