There is a fair amount of information available through the courts.wa.gov - appellate court link. You can look up the docket for the division where your case is being heard (Seattle is Division 1) and you can get a sense of how long it takes to get a decision written and either published or not.
If your matter is being heard without oral argument, that means the court thinks the matter is practically clear and not really subject to fine, nuanced debate. That may make your result happen faster. You can probably expect to wait another month for the decision.
There's no way to know for sure. The decision could come out tomorrow or it could take months. One big factor is whether the three judges are in agreement. If there's a dissent that could hold things up.
By the way, since this is a criminal case, I assume that you're already represented by counsel. That lawyer would be in the best position to assess whether this case is more or less likely than most to be decided quickly.