Cleft Grafting a Mango?

When cleft grafting a mango, does the scion have to be bright green or dark green? What I mean is does it have to be new or an old scion? Also, how much do I water the mango tree after grafting it? I will try to graft a random mango plant I found near the garbage with a Palmer mango. I live in an area with tropical weather so the mangoes grow very well.

Hardiness Zone: 11

By Jose from Dominican Republic