This is a fantastic hike. But you can’t do it independently. Guides are required. Finding the right person is high priority.
Yondering Soles:
… I did my trip in September-October 2017, which is during the peak season in Nepal but just slightly before the real crowds.
Before reading this, please first read my post on the guide to Manaslu Circuit Trek. It is important to first understand about the regulations and requirements for the Manaslu Region. There is also more information on the side-treks you can do. …
MANASLU CIRCUIT TREK : DETAILED ITINERARY
related – our Manaslu Circuit information page
besthike.com 
It is much suitable to add Tsum valley area in Manaslu trekking itinerary. a month trip can be form including Tsum valley and Manaslu round trekking.
Fabulous