How about July 31, 2010? Or if you have another date in mind, just put that.
Just make sure you send your application in as soon as possible. You should already have applied for your extension because you are supposed to apply 30 days before your visit status expires.
I put September 30, 2010. I figure that if they feel that is too long but still want to approve it then they will just shorten it. I just didn't want to seem like I was asking for too long I just really didn't know how to estimate it.
Well I couldn't send it over the Christmas holiday and I couldn't on the first since it was New Year's and then it being a weekend now. I plan on sending it off Monday or Tuesday through express mail and with tracking information. I was told it should be there within 2-3 days. I was told that just as long as you get it in before the expiry date and have tracking then you will still have implied status as long as it is received before January 31st. Of course that doesn't mean I want to wait a week before that date either. I just didn't have much of choice seeing as I was having to deal with everything being closed. Should be good to go on Monday though.