I think the raid will start a level 10. Basically they are going to force you to play all the story missions, the strike and patrol for a bit before they let you play the raid. That was kind of how the game was structured. You did the 5 story missions for each planet. The strike opened up at some point, and then the end goal was the raid. So I don't think they will let you play the raid on day 1. Bungie wants to make sure you enjoy all aspects of the game, not just 1 part. I of course might be complete wrong about this. It's what make sense to me though.