You will see him eat one every few seconds. If you see him staring at the substrate but not picking up anything, there are no pods. Buying pods won't work. You need a tank mature enough to grow them on their own. 9,000 pods would be a weekend snack for a mandarin.
As mentioned adding pods after adding a mandarin rarely pans out well. You might be able to keep things going if you culture pods in a separate tank but you are going to be a slave to feeding it and keeping it alive. Tisbe pods are one of the fastest reproducing pods so that would be what I would recommend.