I made an appointment through the automatic phone system a week prior to the chosen date and time. I will admit that I forgot to write down the confirmation number, but I did call quest diagnostics customer service and spoke with a representative to confirm my appointment the day before. Now when I got up to the Timberlake location here in Sacramento I was told if I dont have that Im not allowed to be seen. I dont think thats fair at all that I have to wait even longer to get seen or worse and schedule for another day. User's recommendation: Make sure you get the confirmation code. And cal customer service just to verify.