Some clarification,

I didn't attend any class for improving English during this process. But in the last 2 months, I did get more practice oppertunities, which I obtained by "forcing" my classmates (native English speakers) from my other class to talk to me for roughly 1-1.5 hours a week. (I don't ask them to correct me or teach me anything during such conversations though.) Besides that, I don't actually have any other real English environment, for I work with Chinese people back in China and Chinese is the communication language.

However, comparing to most working people, I have more flexible schedule and the workload is really light for me. I believe this is a HUGE advantage. It helped a lot, especially at the starting point, -- the first few months of really working on improving one's English.