I have not, in at least 15 years since the grafting had the opportunity to taste the ripe fruit of my Calville Blanc d’hiver. It is situated highest in a reworked standard from Macintosh, above a couple of Belle de Boskoop stems. I’m pretty sure the squirrels living in and traversing through the overshadowing  cedar tree see the Calville from above and cannot constrain the urge to drop down and over the next month dispatch ALL the fruit set. They seem immune to learning, time after time, year after year, that the fruit is not near ripe enough to even want to eat it. Maybe squirrels are not so smart, just acrobatic, and the trait to drop them underripe fruit is the learned exercise, dropping and not so much the object of eliciting something tasty. They appear to eat just a bite or two, then it’s back to the tree to try another-in case something’s better. The previous generations did it, so, so shall we. If, in two legged human kind, we continue to repeat the same actions over and over without learning something, from observing the result, as to how to modify our behavior to achieve a more favorable result … well, you know what they say.  
The Calville is a late apple, I’m thinking late November, but yes I don’t really know, never had one get ripe to be able to judge how it is (here).