@shark2k, the only advertising I've seen for the Roadster is a couple of scans posted here and a few banner ads online. As for the Model S, you are correct. Tesla hasn't advertised the Model S because they currently only make money from the Roadster. Your timeline for advertising the Model S (six to twelve months before it's release) sounds logical and accurate to me.
I'd bet that Tesla has at least some timeline for advertising the Model S planned out, it's just a matter of hitting a few targets before advertising commences.