Generally about 1/2" caliper and a bit over 3’ tall. I think they were in 3 gal pots, though they look a lot like what you got. I’ve ordered about 10 jujube from over the years and there was a slight difference in pot size, sometimes even from the same order.
Some pics of my order from October 2015:
More recent order with juju on own roots:
More general jujube vendor comparison:
Given that Robert is in 6b/7a, we should make sure to caution him to not get GA866. Maybe a Honey Jar and So…