I do fasting at least one time per month(1-3days)
Does it help to gain faster? or it will slow down to build muscle?
In my own experience , it seems helps to build muscle faster
Yup, it seems to help. Your body starts breaking down muscle for fuel once liver glycogen is depleted, so you might consider eating a lot of protein before a short (one day) fast or continue to eat only protein during a longer one.
Fasting/refeeding seems to have a positive effect on glucose tolerance as well as leptin levels, though most of the evidence out there is personal experience.