The best time if you ask me, an almost yearly visitor to this tranquil place - ok now the tranquility seems to be fast disappearing as the townships get invaded by horses if both weekend tourists as well as global tourists and that is precisely why i'd say, having returned from the place barely a week ago that right now is the best time to go. Triund should open for camping this month soon as well. Of course the best months are may and June or for me September to November but it depends on what you look for in your travels. it rains in July and August and those who love rains and hills, this is a good time but be wary of the roads. If you're looking to connect with interesting people from all over the world then anytime between May to Sept is good. if you're looking for less crowded and experience the cold a bit as well, for it can get hot in summer, mid-march is the right time to go but as I found out this time, because of disturbed weather, it was still snowing in Triund, which is one place you'd definitely want to trek to and camp. Due to snow that was not possible this time. I like October for the majority of the travelers leave for other Himachal destinations then and the coming winter has this nice chill at night. It begins to retain a semblance of Dharamkot and McLeod as it was some fifteen years ago.