Fertilizing

My soil is pre-fertilized, with organics, never knew what kind and cant really remember the brand or name.. said that it had all this natural stuff to help drain and such.
I bought some Seabird Guano about 4 days ago, simple organics, smells like shit, lmao. but anyway, is it safe to use very little bit? Even though the soil came pre-fertited for about a month, Im closing in on that... however, just curious if I could give them a lil bit, some of the bottom leaves are a little yellow and I think there lacking nutes... please help.. THANKs

(The mix recommended 1 tsb per gallon, for young plants. I used only a tsp, for a gallon.)