I actually sat down and worked out all the equations based on the mass of my character and the amount of thrust the decanter provided. Our party would be deep in the wilderness somewhere and I'd say " I nip back to town to pick up some supplies, with acceleration and deacceleration it takes me 17 minutes".
Looking back, I think I was a pretty annoying player, but my DM was very patient. I guess he could see I put a lot of work into the scheme. It was also probably the most exciting application of physics I had encountered in my life so far.