The one good thing Lucas did with the franchise after starting it was laying out a general timeline of events that would eventually occur throughout the nine episodes fairly early in the ballgame. A lot of expanded universe material has worked around this timeline rather than trying to supplant it, and barring any kerfuffles, the third trilogy shouldn’t be stepping on too many toes.
But then again, there’s always the option to completely ignore expanded universe, which, generally speaking, is usually the best option short of ignoring the franchise on the whole since a lot of that is a clusterfuck. And hell, even Lucas did that with the second trilogy.