glad to hear rollingriver has finally upped the sizes of their jujus and have plied the bare-root approach... The jujus received from them many years ago were weak premature infants!
would advise to not thin the flowers, since you need as many flowers on your jujus to max out sources of pollen, as well as sites of ovules.. Jujus normally thin their fruits on their own. Of the cultivars, it is the smaller fruited ones which might need thinning(of fruits, not flowers), HJ,contorted's sugarcane, etc.
of course, if you want your trees to grow faster, you may get rid of all the flowers on the first year, but that would extend your wait. For most people that would be 'unbearable'-- if that is a double entendre
on the other hand, the quality of fruits on first year of planting may not be as good as those on the second year, and sometimes the third year.