Unfortunately for you guys. This did cycle my tank. I'm sitting at 0 ammonia 0 nitrites and 20 nitrates. I didn't add anything to the tank but the "live" sand from petco. Only took about 2.5 weeks too. So I'm all set.
Did you mix your own water? Tap water or RO? If you mixed your water with your tap water then your water already have Nitrate in it (20ppm~40ppm is normal mostly in west coast US).
If you bought the water from LFS then there is change they are used tap water and mixed it up in big holder tank then sell it off to customer...you facing the same problem like you mix your own saltwater.
Also, why's Unfortunately for us? You asking question and we giving out advises. However, you can choose to follow or ignore, we try to help base on your information provided.
Note:
Do you sure "live sand" is alive after that bag sat on Petco shelf for weeks, months or even year, i doubt anything living in that bag without Oxygen for that long and your "brand new setup" don't even have any "food" to feed the so called "live sand".