Hi Newbie, I also live in Oregon (near Portland) and seed Wallas (and other onions) the first of Feb. or so.
Onions that are spring planted are harvested the same summer/fall that they go in the ground. I harvest wallas around Sept. 1st.
If you leave them in the ground the following spring they'll go to seed.
If you seed Wallas around Sept. you can put them out b4 the heavy rains come and they overwinter. These finish up earlier than the spring planted ones (Julyish).
-Mark

Excellent! Thanks for the great advice Mark! I was getting nervous and confused as to when to start the seeds so I planted 1 tray today. I figure I'll plant another one in 2 or 3 weeks and see which ones do better. Thanks again! I'll have to remember to seed more in the fall. I'm placing an order for Copra onions soon because I've heard they're an excellent storage onion. Here's hoping for a better gardening season this year!

Yeah, a lot less spring rain would be nice. Last year we had to "mud in" the onions. They didn't like it all that much. :(