April is probably the worst month of the year on all coastal rivers that do not see summer steelhead.
And even the rivers that have summers aren't exactly chocked-full in April. I think the Tuc gets them a bit earlier.
But April is a pretty awesome month for springers. The Willy and C are booming in April. But, they're much tougher fisheries if one doesn't have access to a boat. And if one wants to hit the Columbia, check the regs closely... better yet, have your lawyer do it, since they change them what seems like every 3 hours.
If I was in the northwest corner of the state, and had a steelhead-or-bust attitude, I think I'd stick with the Clack or Sandy. They'll at least have some summers by April, and a handful of springers to boot, although like the coast, April isn't exactly prime.
I believe that some of the southern streams get better early returns, but I don't know much about them.
Now May, on the other hand... pick a river and fish it.