If you have an DL or NWA account number check your status online at delta.com. My wife and I just went through the process for US to DL and were told that it would take 4 to 6 weeks. Less than a week later I checked our accounts online and they were both "Gold Medallion".

I think the 4 to 6 weeks has more to do with the production and mailing porcess rather than the decision process.