I urgently want to reach Shenzhen Fo-Tien from Hong Kong, and to ride the earliest trip soonest!

Dear Sir,

I want to travel at the earliest time to reach Shenzhen Fo-Tien from HK. And I want to take the 1st earliest trip soonest!
Let me know your best advice for details of where, when and how I should board the 1st High-Speed ride from HK to Fo Tian. And, how I can secure tickets nearest from my resident at Fu Shun House, Fu Shan Estate, Diamond Hill?
My final destination is the Southern University of Science & Technology where I will have to start my work at 7:45 am? Please send your advice to my email address at " paulchiankchotmail.com".
Is this advisable to purchase and to-and-fro tickets to return fro Shenzhen to HK rather than buying it separately? My estimated time to return is approximately between 4 - 5 pm every day from Monday to Friday. I also wish to know the fares on each traveling end-to-end-stage (ie. HK to Shenzhen back to HK, reciprocally). Thanks!

Regards, Mr. Paul Chian