Easiest way is to start with Miracle-Gro at low concentration, maybe 1/4 of label recommendation. It is important to make sure the plant is watered and allowed to stand for an hour or two before using fertilizer. Fertilizing a dry plant is a short path to burning the plant. A little fertilizer frequently is much, much better than a lot of fertilizer occasionally.
you could also start off with something low dose like fish emulsion.
Finally, if you have a rich potting soil, you really don't need fertilizer for 6 months to a year. you have taken the time a care to get your cuttings rooted. Don't be impatient, now, and risk killing you hard work. Be patient.