Conditional Formatting: If a cell is blank after due date, highlight said cell

Hi,

I've attached a spreadsheet example where I am looking to implement change.

What I want the spreadsheet to show is if there isnt a "p" in a cell before the week commencing date, I want this cell to be highlighted (red for instance).

This is so i can track if a person has paid and can identify how far behind they are.

So far I have tried this formula within conditional formatting, (E2="","",E2<=TODAY()) and applied this to all columns, with cell ref alteration. This works to highlight blank cells, but also highlights cells with a "p" which I cannot figure out how to stop.

Any help or suggestions would be much appreciated, thank you.

EDIT: I forgot to mention any future dates that havent happened yet, these need to remain white/blank until that date arrives and cells can then change colour if blank