Sorry to disagree, JimJools, I counted back in my calendar, and I get the 8th of August.
24/02/2007 is a Saturday.
There are 3 Saturdays in Feb 2007 before that - 3rd, 10th, 17th - 3 weeks.
4 Saturdays in Jan 2007 - 6th, 13th, 20th and 27th - 4 weeks (7 weeks total so far).
5 in Dec 2006 - 2nd, 9th, 16th, 23rd, and 30th - 5 weeks (12 weeks total so far).
4 in Nov 2006 - 4th, 11th, 18th, 25th - 4 weeks (16 weeks so far).
4 in October 2006 - 7th, 14th, 21st, and 28th - 4 weeks (20 weeks)
5 in Sept 2006 - 2nd, 9th, 16th, 23rd, 30th - 5 weeks (25 weeks)
The 26th August 2006 is 26 weeks back.
The 19th August is 27 weeks back.
So I make it that the 12th August 2006 is exactly 28 weeks before the 24th Feb, 2007.
Depends whether you want to count 3 or 4 days as half a week, so it's the 8th or 9th August, as far as I can tell.
Or is my arithmetic wrong ?