You're not the only one.
I'm not sure if there's a "best" way to get the Joque to fit. What I did was open the velcro waistband and open the leg straps and step into it. I pulled it up around my waist and attached the velcro gently (so I could adjust it). Then I adjusted the leg straps so they felt snug, but not too tight. Then back to the velcro (it was really a back-and-forth process)...I adjusted how high it sat on my hips, and then folded the band under and pressed the velcro together snugly. A few little adjustments on the leg straps and some general wiggling...and I was done.
Then I realized I hadn't put a cock in the harness yet. ::facepalm::
But I found that after the leg straps were adjusted, the velcro waistband was pretty easy to undo and do again. I usually just release one side of the waistband so I don't have to adjust both sides, but that could vary with body size and shape.
Hope that helps. Good luck!