When I went to OCS, I was able to graduate, but not commission because I was injured. Others did not commission because they still had college to finish (they were prior service).
When I went, we graduated in Woodland Camis. This was one ceremony (one that I got to sit on the side-lines...)
Then the people that were commissioning commissioned in their Service Alphas. This was in the winter, so in the summer it may be Service Charlies.
When you graduate, you will either go back to your unit (if you are prior service), check immediately into TBS, or go back and work for your OSO. I explain a lot about the TBS check-in on my TBS page!
When I went, you could invite family. Because of COVID, I don't know if that's a thing now.