Hello! I started two small tanks last November using TBS sand and rock, so maybe I can help. You absolutely do not need to add any additional bottled bacteria to your system; you paid A LOT of money for that sand because it's teeming with microbes.
I think what other posters are suggesting is that because you used the live sand, your tank is essentially cycled, but you're not yet seeing nitrates because there's not much for ammonia at this point.
When I started my tanks, I definably had something of a 'mini-cycle' that really lasted a couple of weeks. There's so much life in the TBS sand and rocks, and even though they ship it quickly and carefully, there is without a doubt going to be die off. This die off, in my opinion, is all the ammonia you need to get your tank going.
For dry rock and sand, I'm a fan of bottled bacteria and bottled ammonium chloride, but I WOULD NOT add the ammonium chloride to your system. I'd be afraidyou'd add so much ammonia that you'd cause more die-off of the microbes you're hoping to cultivate.
In this case, I'd ghost feed some flaked or pellets, and see if you start to record some nitrates.
And FYI - You're going to love the rocks when you get them
Good luck with your tank!