Ten years ago I planted a half dozen Lilacs.
Two were tree Lilacs and the other bush type. One was Beauty of Moscow
Depending on how large yours were, mine were very small to really just twig, It takes years for them to develop -- usually.. The twig did not make it.
It takes years for them to develop -- usually.
Sadly my BoM seems to have a slow moving disease and I am going to rip it out.