Well anyone can help me PLEASE

My SPOUSE visa expires.......20th June 2009
I entered UK .....................19th Sep 2007

WHEN, should I apply for my ILR??

I know its 28 days before?????? (BUT what date??)

I live 15 mins away from Croydon, so I shall NOT be posting my application, I shall be taking in person.

Thanks to all in advance.

P.S.
Hubby wrote this, my grammar is NOT that good...yet...LOL