Agonise no more. Instead, pick your medlar when it will easily twist off from the stem. Be it hard as a youthful opinion, worry not. Shove it and its companions in anything you wish, even a save-the-earth bag, and pop them in the freezer.
Then take out, after they have frozen, as many as you like. It's easy as that.
The flesh colour will be mostly blandly blonde, and the taste will be more like a baked apple than a naturally bletted medlar, but what can you expect from a miracle? Real depth of beauty, taste and natural rot can only be reached by experience.