Help with Harlow Hat

Hi everyone! I just started the Harlow Hat by DreaReneeKnits. It is my first ever brioche hat. It started with a tubular cast on and after the two set up rows, it asks for you to join in the round (which I have done a million times). The thing is, I am not sure how to proceed. I have joined in the round a million times, but never in brioche. The first stitch calls for a yf-sl1yo, k1. How do I join in the round if that is the first stitch. Or is there a method I am missing? Am I even making sense lol? Thank you for any help you can provide.

You can join as given in the pattern. The knitting won’t be securely joined until you work the k1 but that’s ok. The next round should firm up the join.