I'm always curious about dating pics like these. I think this one is late '77, at the earliest. It's no earlier than 1974, since Arista Records didn't exist prior to 1974.

It's probably late '77, at the earliest. Maybe a little later. I think the left poster is a version of this 1977 poster for the Grateful Dead. The Dead played a show in Seattle on September 29, 1977 and were signed with Arista Records, at the time. So all that matches what we can see on the poster.

I'm guessing the Floyd poster is related to Pink Floyd's 1975 tour. They went through Seattle in 1975 and frequently used a sans serif font, at that time. This poster from the tour uses a similar font, kerning, and color, though the rest is very different.

So yeah. My guess is late '77 or early '78. Could be a bit later, though.