Delivery Schedule of Tickets

Hello,
I am travelling to China from February 13th - 28th and intend to use the train quite a bit. However, I have a couple of concerns:
1) I am aware this is a busy period for travel in China due to the New Year. If I book through your website what are the chances of me getting my first choice tickets?
2) I plan to stay in Beijing until Saturday Feb 16th, and make my last train journey on Feb 22nd. If tickets are only released 12 days in advance, does this give you enough time to send them to me before I leave Beijing? Or should I place 2 separate orders and get the later train tickets at a later destination?

Thank you