Bullet train ticket Shenzhen North to Zhangzhou

I am going to Shenzhen next week 10th November, can I buy my Bullet train ticket from Shenzhen North to Zhangzhou departure 29th December 2016. from the Shenzhen Railway station counter at Lowu. (I am going to Zhangzhou from Shenzhen in end December).
Or can I buy above tickets traveling on End December at Shenzhen Railway Station instead at Shenzhen North Station. I am gong to Lowu next week.
thank you