Welcome to Monarch, and to the forum!
You can select/reject data from your report in two places - in the report window by setting traps in your templates, or in the table window by creating formulae expressions.
In this case, it sounds like you might be best off trapping all the data, including the older records you don't want, in the report window.
Trapping in the report window is based on literal, wildcard and NOT traps, and doesn't let you specify a range of values to capture.
In the table window, there's not much limit to what you can do with filters.
Hope this helps,