Excel Newbie: spotting trends in 3 month rolling period

Good morning!


I'm trying to create a way of finding employees who have had complaints put in against them in a set period of 3 months rolling.

I have the first column as date of report and the next few as staff name because some complaints have multiple staff involved and then the subsequent columns as variables such as location of complaint and nature etc. This is in order that I would be able to find trends in the data.

I need to come up with a formula that searches for the same name occurring 3 times within a 3-month rolling date range but Excel is not my strong point, if anyone could help that would be amazing!