Grafting is a fine balance between drying them out before the rootstock comes awake for the year, and waiting too long before and having the graft dry out before waking up. Both collecting the scion and grafting it. Northeast area atleast, you can fall grafting in late august early september. However, buying or getting rootstock is a late winter / early spring thing.
If you can get rootstock now, either plant it where it will be permanently, or put it in your backyard. Anything uprooted and planted now will need to be watered every few days. June / july planting and letting mothern ature take over will likely not end well right now.
Grafting can be done at any stage of life in a tree. Plant your dlgo or P18 and graft it net year. Or graft it this fall, it fails, then graft again next year. Separating transplant shock and grafting shock a year apart makes it easier I think.
Do not call it a bad graft too soon. Had some grafts taking and leafing out in april. Sometimes, the rootstock wakes up, then makes leaves, and then sends life to the graft. In the northeast could be anywhere from april to late june. Sometimes you ned a good rain or two before the rootstock has engh energy to wake up that graft. Thought I had a dud tree from lowes this year. The keiffer pear was looking dry. The day i was going to return some unused lumber mid june I was waking to the tree to uproot it, it had buds coming out. This tree was dormant vs other trees at the store and they gae me 1/2 off the tree.
