Hi, how long does it take to get from the Futian Checkpoint to Shenzhen North Station via Metro?

Better still, what's an estimated time to get from Central Station or Hong Kong Station to SZ North Railway Station via the MTR and Subway? We have to catch the 12pm Bullet Train to Yichang to start a Yangtze River Cruise and don't want to miss it. My concerns are the Hong Kong Rush Hour (06:30 to 09:30) and holdups at the Border Crossing. Thanks.