Just took the tape off, here you can see the graft line:

The top already flowered and set a few small druplet fruits.

There are a fair number of blossoms on the Bing too right now:

The bloom times did overlap, but obviously the Royal Minnie part bloomed much earlier than the Bing.

Last year (before the graft) the Bing put out blossoms as well, and eventually got to be quite full of big healthy leaves. But the tree started leafing out very reluctantly, only a small number of tiny leaflets, about half of which got baked in the sun and had scorched tips, even when they became a little bigger. Last year the leafing began before any blossoms appeared. But this year all the blossoms appeared first.

This is in climate zone 10, south of Los Angeles, so we don't get much chill. Virtually no one else growing cherry trees around here, so it's very much something remarkable. Maybe the Bing will be able to produce fruit (in coming years) now that a section of Royal Minnie has been grafted on top.