Hi SIMMS7400,
I will have to assume that you have everything under control and do not desire any further help from me. I have asked three times what shell you're using and have not received an answer. Therefore, I am unable to post a good suggested suited to your environment.

I suggested a simple way to calculate the calendar quarter from the month number (in post #10) and in that same post showed simple ways to calculate the month numbers for the three months in that quarter. Instead of using that code, you used other code that clearly calculates quarters incorrectly. (And, the code you showed us in the 1st update to post #13 still uses that incorrect calculation three out of four times when assigning values to _PQ.)

It is clear from your examples, that your definition of FirstQtrWeek and LastQtrWeek is a date that is not in that quarter with the possible exception of cases where the 1st day of a calendar quarter happens to be a Saturday. Your refusal to clearly define how those two values are calculated (instead of just giving ambiguous examples) makes it impossible to suggest code that might meet your requirements. Given that you say that 12/31/2016 is in Q12017 while your calculations (which are purely based on the month number) clearly compute that anything in December is in Q4; I have great difficulty correlating your stated requirements to your code.

I hope that some of my comments have been helpful. I won't bother you with more questions.