Give them some time. They may need a couple years to get well established before they start blooming.

Also, after blooming, lilacs go into a growth mode and form the buds for next year's blooms. So if you prune, prune right after blooming--not late in the summer or early in the spring as you will remove the blooms. The same would apply with your new bushes--don't prune later in the summer or in early spring or you may take off any buds that have formed. If you need to prune non-blooming bushes, either trim new growth while the stems are still succulent or do it early in the year so that you don't take off later growth with next year's buds.

Lilacs also like lots of sun. If they are mostly shaded, they won't produce many if any blooms.

Good luck and concentrate right now on having healthy bushes.