I do the squares first because I square up my blocks before assembling them. I'm not perfect even tho I try I always square up so all my rows go together perfect....Im not a fan of fighting with fabric at that point!! I do find on a big project that if I strip piece the blocks in stead of doing one full block at a time makes it less boring. If possible sometimes you cant and have to do one block at a time. Good luck king size wow!