How much time will I take from Hong Kong to Century Plazza Hotel in Shenzhen?

If you start from the downtown area of HK and take MTR to Luohu, it would take probably 70 minutes including the time you go through the Luohu Border.
If by bus, it would take about 1.5 hours.
BTW, the hotel is located 1,300 yards north to the Luohu MTR Station. After you go through the border, you can whether walk to reach or take a taxi.