Why can't you just answer yes or no?
When someone says God is omniscient it means that God is ALL knowing. The yes or no answer to any subsequent questions of “did God know” has thus been answered in the affirmative. Re asking a question of “did God know” requires no additional answers of yes or no. All means all, not just a little bit of all or just a part of all or even most of all. It means all as in God knows everything there ever was to know, everything there is to know and everything there will be to know.