Hi, I'm in Hong Kong and I'm holding an Indonesian passport. I want to go to China mainland.

I'm applying for a visa to China, but it only allows 15 days in China. I need to be in China on 17 December 2014, But my flight ticket back to Indonesia is only on 7th January 2015 (which is more than 15 days). I'm planning to extend it in China, so that i won't get fined. So do you know if I could go to China on the 17th of December(will the immigration find out?) Or if I can only enter China on 22nd of December?