The Chinese Spring Festival will be ended today on Feb 17, so no need to worry about the crowds. Upon arrive at Shenzhen Airport, you should follow the direction to take the shuttle bus Line 1 (330 bus) and get off at its terminal on Shenzhen Railway Station. Here, you could transfer to a bullet train to Guangzhou on the spot. Remember to purchase the train, the terminal of which is Guangzhou Railway Station which is in Yuexiu area, not the east station.