There's a good chance the requisite bacteria are ubiquitous in the air and the trees will self-inoculate. If you start them in pots and repot or plant out at some point you can get a look at the
roots and see. Active nodules
should be reddish inside. I did this with mimosa here...planted seed in pots, Acacia too, and both were nodulated by the time they were ready to transplant. You could also look for nodules on established trees of the desired species or close relatives, and mash these up with some
water and drench the roots of your seedlings as an inoculant. Some simply add some soil from beneath mature, nodulated trees to the seedling mix.