Return Heading Ascociated With Date Found In Table

Attached is a very small sample of a workbook that looks at community impact; before, during and after a project.

The source data (not shown) is down loaded from a system that can only supply the date in reverse order (see column A).
i.e. 20080229 = 29-Feb-2008. I've applied a conversion in column "C"....

= DATE(LEFT($A2,4),MID($A2,5,2),RIGHT($A2,2))

The 'properly' formatted date is then used to determine when on the scale of observation that given date falls.
e.g. the number of weeks before, during and after the project.

This is determined by the 18 week date 'matrix/ array' in columns F to X the red box is used to input the project start date, (& assumes the project runs to its normal 6 week time scale, it get REALLY messy if the boss prolongs or cuts short the project!)

From the result various figures and a graph using the properly formatted date are calculated, produced and presented showing....

The scale of the problem {before}
The impact of the project {during}
The lasting efftectivness {after}

You can see that I've managed a 'workaround' for the limit on the number of IF statements allowed in one formula using a rolling formula in columns; B then Z - AQ. This works OK, but!! combine that with the other formulae doing the impact calculations and 20000+ rows of data (with the acssociated workings in B + Z-AQ) the effect is to make make the file over 15Mb for 1!! worksheet, (the limit for emailing on the jobs system is 3Mb!!) & just to really make it scary sometime there are 2 projects on the go at once.

Before I created the attached the user responsible for these graphs and calculations manually counted dates & typed/copied & pasted the week number/tile, initially several days work followed by half a day every weekly update!