You may travel to Guizhou during November which is usually the new year festival period of China Miao Nationality(https://www.travelchinaguide.com/intro/nationality/miao/) in Guizhou. It is a very important fetival and you can see Hmong celebration during the period. Well, Spring is also a nice time to travel there since there are many festivals will be held during this season and the people always has Hmong performance.