Dear sir, you are suggested to book the air tickets as early as possible, since it is the Spring Festival transportation peak period during your requested days. What's more, there is always the largest passenger flow volume in China between the two cities. I just checked that there are some discounted tickets available on your departure date. And it takes only about 2 hrs by flight while almost 10 hrs by train. Thus, if I were u, I will book the tickets directly online.