If it's a Signature, then your VIN will contain the letter 'S' just before the number (i.e. ...S01088). I believe the Signature series was for the first 1000 (or so) reservation holders, which is
not the same thing as the first 1000 (or so) cars off the line. If memory serves, there was a Founders' Series first, plus non-Signature cars for demo/loaner purposes. Your VIN is not, and never was, an indication of what order your car was built at the factory. Only Tesla knows that for sure.
So, it doesn't matter that your VIN is S01088, or S44088, it's still a Signature.