Date for sending notice:Companies Act Doubt

Suppose , the date of AGM is 28th  September 2009 and the notice was posted on 6th September. is the notice valid?

My contention:

It shouldn't be valid as the notice should have been posted on 3rd Sept. at the latest. But the answer too the question that the notice is just 1 day short.

In MP Vijaykumar book;" the notice for 27march should be posted by 2nd march" is said.

Which one is correct and how.