When to renew PR card?

Hi all,

I will appreciate if any help! I have been living in Toronto since August 2006 and my PR Card will expire on September 2008 which means that I am in my last 2 years of 5. My question is when can I renew my PR Card? Do I have to wait until right after I stayed 730 days, which will be very close to my PR expiration date then I can renew my PR Card or can I apply sometimes earlier, that's say a month or two prior than that?

Some says you can apply renewal as earlier as you can, but I guess that applies to those who has stayed at least 2 in 5 prior his/her renewal application. What about my case that I stay the last 2 of 5?

Thanks in advance!

KF