I don't think Saver allows you to standby for a later flight unfortunately, but someone can correct me if I'm wrong.

Also, if you're doing Global Entry enrollment on arrival, it's not processed instantly, they have to do their checks and it could take some time, so you will notget pre check.

I don't travel through PDX a lot, so more frequent PDXers can chime in, but every time I've flown out of there, even with pre-check it's been an absolute s**tshow. I travel weekly all over the US and PDX has probably been the most consistently terrible TSA experience. As early as it is, I'd get there 2 hours early.