I searched this site and couldn't find the answer. Any help would be greatly appreciated!

From Jan 1 to July 31, 2008, I was on OPT, thus a non-resident alien.
On Oct 1, 2008, my immigration status was changed to H1B.

I know if I file tax return now for year 2008, I will file as non-resident alien, and I can claim $5000 US-China tax treaty for my wage during OPT (I did this in the past years when I was a student).

But I would rather to extend my tax return until June so that my wife and I will pass the SPT and become resident aliens. Then my wife and I can treat us as resident alien for the entire year of 2008, and file jointly to claim the standard deduction (my wife has no income).

My question is that: if we file jointly as resident alien, can I claim the $5000 US-China tax treaty for my wage during OPT, apart from the standard deduction? Considering the "saving clause" here:
http://www.irs.gov/pub/irs-trty/china.pdf

Yes, you CAN claim the $5,000 treaty exemption even if you file jointly with your wife under an exception to the savings clause.