Piecing strips together

I am getting ready to piece this (http://www.bernat.com/pattern.php?PID=180 ) together. Would you was and block each piece separately first?

According to the website that yarn is acrylic, so I would think that you could go ahead and assemble then wash and dry. I don’t think it would need to be blocked. I have never blocked an afghan I made in a manmade fiber.

I should have said what yarn was used. I used Bernat

Does anyone have advice on whether to block then join?

I would probably join first. Just be sure when you do it that you keep the stitch count even on both pieces.