also can say how long is the total waiting time?
any customs check in hk or go to china then check?
I took the HK->SZ Futian route last month. This was a trip on Friday afternoon, so not too busy.
Waited for 2 minutes for ticket collection, then went through ticket and security check, another 2 minutes. Took the escalator down and went through HK customs. Didn't need to queue and there were many counters open. Walked a short distance through no man's land to China customs (air conditioned), had to fill in the yellow entry form, took about 6 minutes for this part.
Since they recommended to arrive 45 minutes earlier than the scheduled time and I had gone through the immigration process in lesser than 10 minutes I had 30 minutes to burn in the waiting area. When your train is boarding they will make 3-4 announcements and the lao aunties at the platform entry gate will also start asking around who is taking the next train.
The train took 13 minutes to reach its destination.
The whole process is staffed by English speaking staff and they were really professional and friendly. I have had a good impression of high speed rail in the mainland previously, I would say that despite being costly compared to the MTR, the high speed rail station at Kowloon is the most comfortable way to get from HK to nearby Chinese cities.
When I got off at Futian it was quite amazing how large the station was. You are in the large underground walkway that is connected to all the nice malls in the Futain area, additionally u can take the green, red or blue line from Futian railway station.
Just a warning for those travelling with disabled/elderly though, the SZ metro stops are about 500-700m from the railway station (maybe I took the wrong route)