How to use functions for calculating dates of other cells

Ok so the formula I am trying to write, I hope it's possible.

So in cell A1. I have a received date that is entered, like a date a file was received.. Then in B1 if a date is not entered in that cell within 8 business days of the date in cell A1, then B1 will turn red and there will be a -1 (on the 9th date), -2 (on the 10th business day). So essentially B1 if no date is entered and it has exceeded 8 business days from the A1 date, there will be a negative number for how many business days it is over 8 days.

I hope that makes sense. If I need to create multiple cells to achieve this let me know.


Thanks!