What to expect
Water draws the eye here: the Cañete runs through highland scenery with cascades and villages such as Huancaya. The reserve spans parts of Lima and Junín. Start with the places where you want to sleep and walk, rather than the vague intention to ‘visit the reserve’.
How it fits into a journey
Pick one part of the area first. Lunahuaná may fit along an approach, but staying there is not the same as staying near Huancaya. Do not make an onward flight depend on an unconfirmed return from the mountains.