They should go into your fridge, not freezer. The reason February is a good time is because the tree should be fully dormant and that's about the latest you can count on that. Too early and they spend more time in storage during which they can mold or dry out. With good storage conditions though both are manageable. You want relatively straight new growth that is hardened off and dormant. Maybe pencil diameter in lengths perhaps 6-12" long. Store them in a ziplock bag wrapped in a barely damp paper towel. Put them in the fridge. Every month or so, check and verify that there is still some moisture in the bag and they aren't molding. In the early spring graft them onto another tree or rootstock. Or just buy another King apple tree. It will be the same effect.

I have read that in this instance that people can do two grafts. The native variety being the most hardy and strongest rooting, then a short intermediary piece which can bridge between the native and fruiting varieties. Can anyone assist? Or know someone who can? I have cut down a large native cherry and would like to graft lapins and stella to the sprouts which are sure to come up this spring. "example taken from plum/almond stone fruit grafting" - " Also (and this is where the fun starts) most fruit trees in the Prunus genus are sometimes compatible with each other: almonds, apricots, nectarines, peaches, and plums all are compatible for grafting, but occasionally it's complicated. For example, some plum rootstock is not compatible with peaches or nectarines; and some almonds require an intermediate step before grafting onto some plum rootstocks."

First, I would start a new thread that addresses "looking for citrus rootstock"; you might get a lot more responses. Second, be sure you understand what rootstock you want; as in dwarfing rootstock will give you another dwarf orange, while standard rootstocks will give you a standard size tree. Also dwarf rootstocks tend to grow slower and take longer to make fruit.

You don't show how much tree there is on top. If the grafts are low and there is a big tree on top the grafts may live but will not grow enough. Just look at a big tree and notice how those small low branches never turn into big ones.