Warm welcome from the Pacific NW. I agree with Claudia, your best advice will be from a local reputable nursery or yard service, who will be familiar with your particular micro climate. There is always an optimal time to plant, but sometimes we have to work around that, and the key (in my opinion) is to water DEEPLY at least 2-3 times. You may also want to shade them from the harsh afternoon sun and/or drying winds (if you have any) until they get established, although you will be the better judge of that in your particular site. Good luck, sounds lovely.
