I have learned it since I came to China.

自从我来到中国，我就开始学了。

youdao

I came to China three weeks ago.

我三个星期前来到了中国。

youdao

I came to China last week.

我上星期来到了中国。

youdao

When I first came to China, the conventional wisdom was that pizza would never catch on here.

FORBES: Pizza Anyone?

Beijing (CNN) -- When I first came to China 39 years ago, airlines distributed cigarettes free of charge during flights.

CNN: China clouded in cigarette smoke

When I first came to China almost 20 years ago, a Chinese partner could not be expected to make its equity contribution in a joint venture in cash.

FORBES: China's Coming M&A Boom