Does anyone has any idea how will the traffic be like on 1st May (start of golden week & World Expo)?

I will be in Suzhou on 30th Apr, while my plane is leaving from Pudong on 1st May 12noon. I'm thinking of catching the 7am long-distance bus from Suzhou to Pudong on the morning of my flight. The estimated time given for the bus ride is 2hr 40mins (which puts me at PVG at 9:40am); however I am worried about the delay if traffic is exceptionally heavy.

Thanks in advance for any advise.