Counts given criteria

[erahi]

I have data that shows the all the store visits made by each person with their timestamps and looks like this:




I need a formula that will work out the following in two separate columns:

- A visitor who has made at least 1 visit in a 6 month period
- A visitor who has made 6 or more visits in a 3 month period

I'm guessing I would need a COUNTIFS with an IF formula....

 

[erahi]

In Column A I have the Person ID and column B is the timestamp of the visit (e.g. 23/4/2017)