Once the buds start to swell or break on the tree your getting grafting wood from people have better luck t-bud grafting. T-bud grafting is where you look for a non leafed out bud on a non dormant tree to use as a graft. T-bud grafting is where you take 1 bud during the non dormant season and graft it to a non dormant tree. You might see this tutorial T-budding tutorial. Grafts such as cleft, bark, whip and tongue, and saddle graft are done using a dormant scion that is preferably pushing no growth at all and has no bud swelling and joining it to a tree aka rootstock that may have some swelling or a small amount of growth. You might see this link https://m.youtube.com/watch?v=7blxoFfJC4I and this post Top working Pears weather permitting . The more dormant the scion the better your chances of success. The new scion wood gets a bath in 10% bleach and 90% h20 to prevent disease transferral. The rootstock has roots and things such as that not suited for a bleach bath. Most orchàrdists spray different things such as fungicide or pesticide on the rootstock to prevent disease.