Bus from Shanghai to Huangshan

Hi, I am planning on taking the bus from Shanghai to Huangshan on the 6th of february. But you can only buy this tickets on the spot at the day of traveling or maybe one day ahead. Do you think we can make this? I'm very worried. And we also take the train on the 10th and 14th of february, how many hours in advance should we arrive at the station? I am scared the crowd will be so hudge we won't be on time.