I would only wait if it will raise your GPA in a significant way. One class probably won't do that.
That said, I did wait for my final quarter's grades to come out before submitting my application. They came out in late June and I submitted on July 1. I got a 4.0 that quarter and it bumped my GPA to 3.6/3.6. I considered that to be significant enough, and utilized the extra time to refine my PS. The downside was the extra processing time that it took for validation because I had submitted later. My application wasn't validated until 7/24.
If the rest of your application is in good shape and you're confident with it, and if the grade from that class doesn't really change your GPA, I would just submit it when you first can. This will get it sent out to the schools asap as it should be validated rather quickly throughout the first couple weeks of June (I remember seeing most people with 24-72 hr turn around times during the first week, which is much better than the 3 weeks it took for mine). That way you'll get a jump start on secondaries.