Queries :: Appointment Activity - Select Query For MAX Date

I need to find the frequency of client's appointment activity after their last appointment in a 4 month window.

My question is:
(1) Is my SQL going to give me the last time a client was in the office within the 4 month window?

(2) What will my SQL need to like to count frequency of appointments before and after window for each client?

(3) Can I do (2) in the same SQL shown above or will I need to make a new SQL statement?

Code:
SELECT tblTest.Client, Last(tblTest.AppointmentDate) AS LastOfAppointmentDate INTO tblTest
FROM tblTest
GROUP BY tblTest.Client
HAVING (((Last(tblTest.AppointmentDate))<#4/30/2014#))
ORDER BY Last(tblTest.AppointmentDate);

Details

Date Window I need to select the clients last appointment: Jan 1, 2014 - April 30, 201

Once the last appointment has been determined for each client in that window I need to count the frequency of appointments before and after that date.