If you can, search online for the specs of your servo. Find out it's electrical specs under load/from stall, then return the power supply you bought and use the money to grab a power supply that matches the values you saw on the spec sheet.
EDIT: I find it ironic that I am posting servo motor advice for you here, while simultaneously having a post right next to yours looking for folks with servo motor experience to help answer questions I have. LOL. As such, please take my experience level into consideration when following my servo motor advice- I would hate to hear I steered you wrong!