I do my first one around 500-1500 miles to get any metal particulate (or sand from the sandcasting) out that may be left over from the engine production process, then I typically do one at 5,000 and then every 7500 after that. I also change my oil filter at every change. This timeframe is assuming you are using a full synthetic oil. The dealership/shop time frame is probably generic and just spits out 5,000 (all 3 of my jeep wave oil changes at the dealership came with 5k recommendations, despite using the full synthetic mopar oil. I disregarded them). I also immediately change all of my fluids on any used vehicle purchase to make sure the guy before me didn't use the wrong stuff. I write the mileage at which i did the last change on the side of my TJ filter for reference, but with the JT I just do it when it hits ~25%. I'm pretty sure the newer jeeps calculate that percentage solely on mileage.