Shenzen tour. Is it enough for one day

I will travel with my family and friends (4 adults and 3 children), to Shenzen from Hong Kong on July 8. None of us can speak chinese. We have emailed the hotel and if we want to hire the tour guide, the tour will start only at noon which is late because we will be in shenzen for one day onlyl Is it advisable to go to Shenzen without a person or a guide who can speak Chinese? We plan to vist wonder of the world and happy valley. Is it enough for one day? And where is the best place to do shopping in shenzen?