Two things;
A degree or two of temp is not an issue for a healthy fish. What is most important is the stability of your parameters after 24 hrs. Measure your pH out of the tap. Then aerate the same water for 24 hrs and measure pH again. You want those two measurements to be in line.
Second, local fish is not as important as healthy fish. I know my water parameters are different outjofnthe tap than my neighbor around the corner, every situation is unique. In my expierence nothing makes Discus keeping easier than starting with healthy stock. The vendors here are top notch and should be the first stop.