hi my friends i wonna know when should i file to remove the condition on my green card it will be expired 06/13/2008 i m confused shouid i file exactly on 03/13/2008 or 03/15/08 is it 3 months or 90 days thay u for your help

it's 90 days counting back from your green card expiration date.

Yes, that's correct, 90 days before. If you file it early they will send it back to you. I filed 30 days too early and my whole application was returned. (and I was stuck paying the "new" rates )

Here's a very helpful website that you can use to determine when you can file your I-751.

It's 90 days. But note also that that's the earliest day on which you can file. You can file any time between that date and the expiration date on your green card. It's prudent to file relatively early in that window, for various reasons, but it's perfectly OK to file a few days after that opening date. If you file a week after the window opens, then the difference between 90 days and three months becomes irrelevant.

you can file even its 4 to 5 days advance! Mine expired October 4, but I sent my application by June 29th instead of July 4th.