Right, you can do a fishless cycle. Add ammonium chloride until you get to 2.0 ppm and add some of the bottled bacteria to help speed up the process.
DrTim's Aquatics One & Only Live Nitrifying Bacteria for Cycling Aquaria, Salt Water, 8-Ounce https://www.amazon.com/dp/B002DVRHMS/ref=cm_sw_r_cp_api_bpLFybHD70F8P
I wouldn't get it on Amazon though. I got the same size bottle from @robert4025 at Neptune for 1/2 the price.
So what is the difference between API Quick Start and Dr. Tim's One & Only? I thought they were equivalent products. And we will be partronizing @robert4025 soon. We have Neptune on our list to ask about the lighting (weighing DIY vs. Current USA Orbit Marine).