How late can you graft dormant scions onto a tree?

When I went to shut our last cooler off on July 18th, I discovered a bag with 5 varieties of pear scionwood.  The scionwood would have been cut back in late February.   All the scionwood was still green and viable.   I decided to graft it onto a Moonglow pear tree.  I took the pictures below tonight.  As you can see in the pictures, all 5 grafts appear successful.   It seems that as long as your scionwood is dormant and viable that you can top graft a tree long after it has broken dormancy.   Fun experiment.