Is is to late to top graft a pear tree?

I took the grafting class this spring. First, the class was great. My two little pear trees are growing!

I cut off a 6-inch limb from a crab apple tree about a month ago, and top grafted (or is it crown-grafted, I have my literature from class at home) some apples. I didn't want to cut up any more trees until I knew whether it would work. Well, the scion twigs are now starting to sprout.

My next project would be to do the same to a mystery pear tree that just has a few hard pears. But is it too late in the year? Can I expect the scion twigs I picked up at the scion exchange and have had in the refrigerator since then to still be good. Anything else I should be aware of.

Thanks very much.

First off - congratulations on your baby pear trees, and your success with "Crown Grafting!" I'd shown some of my work at the spring class in hopes of inspiring just that!
Advice; allow each sprout to "go wild" this summer - you'll "tame it" this Winter! And, this Winter you'll need to bend and tie over those sprouts to form permeant limbs. Try to give equal sun exposure to each, or just expect a couple to eventually dominate while the others simply heal the wound.
Your "next project:" (an excellent question) YES, those stored scions should be perfect for grafting! And it's only a few weeks past prime Bark Grafting time. You simply need the bark to "slip," and your scions dormant. This allows you to: make your cut - deep - right into "the wood;" carefully peel it back; insert the scion (I'd suggest leaving only 2 buds); tack it in place using a small nail with a head; (plumbers) putty the remaining gaps, and seal with a latex grafting compound (don't forget to dab the scion tips with sealer). I assume you'll do whatever just worked for you - but that's the basic process.
My first concern would be "sunburn" this "late." But as of late (in Western Oregon) - no problem! But you may want to consider shading the tender sprouting scions of your next project (the 1st ones should be fine) if we get some real scorching sun. Second; when Bark Grafting, remember, you're working close "inside" the tree where, once leafed out (as now), far less sunlight penetrates. As the season progresses, make sure all the Crown Grafts are receiving adequate sunlight, competition from nearby water shoots is not good. Let the desirable wood dominate!
Otherwise - keep us posted