I’m late to the party but this i what i do.
I play the montage with a play rate of 0. Even with a play rate of 0 the blend will still happen. Then i use a delay node to allow the blend to finish. Then i play the montage again at the normal play rate.
Now i have a full blend and the montage plays its full lenght. The blend in does not “wash out” the beginning of the montage.