Growing from seed is a bit painstaking, but quite rewarding due to the time element involved and the sense of propriety. Where we are at(las vegas), we have been promoting jujus, but we cannot declare it “jujube country” until we’ve actually developed our own novel cultivars from seed. We now have this proprietary vegas series of sorts: vegas booty, vegas candy, vegas spicy, v. glitzy, v. sweetie, v. bounty, v. kinky(from contorted), and v. baby. And should one of our seedlings from sihong and hj produce decent fruits, we’d respectively name them v. lucky and v. honey 
Anyway, have sown more than a thousand juju seeds over several years. Jujube can start blooming at 6 months of age(have a pic of 6 month old blooming juju in this video), but so far with the most precocious, the wild-type characteristics are exhibited; smallish fruits,very thorny. Those with genes for bigger fruits usually take longer, bearing on their 2nd or 3rd year. I could be wrong of course, since at least one seed-grown juju started bearinng bigger fruits as it matured.
below is vegas spicy on its 2nd(3rd year?), which had really spicy but smallish fruits on its first crop two yrs ago
then last year, some of the fruits got substantially bigger(below pics), and while it retained some spiciness, it was also considerably sweeter. A little disappointing(due to decreased spicy trait) but at the same time promising(due to increased brix and size)
