I plan to apply HongKong visa, my travel is fixed for December, should I apply in September or wait until November?

You should apply for Hong Kong visa in early October, generally speaking, applicants are advised to apply Hong Kong at least one month before the travel because it may takes 4 weeks for processing. Sometimes, the Hk visa application needs the approval of Hong Kong Immigration Department. You can buy the flight ticket before applying, the transportation arrangement, such as flight ticket is required for Hong Kong visa application. You will be given at least 14 days stau duration.