matured/seasoned juju wood grafts will generally bear flowers even in the most hostile conditions(drought and other stressors as recent bare-root conditions or recent grafting, etc), and will just drop them if the plant is not ready. It is almost a given that leaf production equates to flower production. So really intriguing to hear that @k8tpayaso 's lang did not bear flowers, since i found it to be the case with some of our lang's as well. Seems to be the only cultivar we've grown that is 'capable' of bearing leaves with no flowers at their axils.
Even seedlings as young as 2 years of age will already be bearing flowers, and from @k8tpayaso 's first hand accounts, some seedlings will bear flowers on the first year of the seeds being sown. Incidentally find it amazing that a fruit tree with a productive life of several hundred years actually starts blooming at 1 or 2 yrs of age-- from seed. One of the few fruiting plants i know capable of doing that