Trying to take sample readings based on time
 

I am creating a chart that has weekly intervals
Let us assume to start the active cell = f18 then I will fill down

I am trying to get excel to compare a cell (E18) on a weekly basis to Now().
If it is the same day then then read and write the value of (P8). If now() <
E18 it should return "". But my challenge is when (E8) Now(), I want to
retain the prior week's reading.

For example:
the reading from 11/09/2007 was 1002; 11/16/2007 was 1063. The Next reading
should be on 11/23/2007.


Thanks in advance,
Rich Webb
Issaquah, WA