I understand copy stands are pricey. I would recommend a tripod with a 90-degree column and a ball head instead. Rather than move the camera to fit the coin, you move the coin to fit the camera. The gross adjustments are made by placing something under the coin to get it in the ballpark, and, if required, fine adjustments are made with a lab jack beneath it. You should always use manual focus. A tripod is effective but bulky, inconvenient, and generally frustrating for this kind of work, often taking the fun out of it. (If you plan to do this with any frequency, invest in a copy stand.)
Regardless of how you support the camera and the coin, the distance between the coin and the camera lens depends on the coin's size. With a macro lens, coins under 1" in diameter will not fill the frame, but you'll be at your minimum focus distance anyway, so there is nothing you can do about it. If all your coins are under 1", you'll only need one coin position relative to the camera. However, as your coins get larger, you will increase the distance between the coin and the lens to fill the frame with the coin. I constantly reposition the camera to get the maximum pixels on each product.