There's no such thing as a fast way to break in a catcher's mitt. It needs to get beaten by fastballs.
Do NOT try any mythical methods that people have tried over the years --- for example, soaking in water, baking, microwaving, using "glove oil", shaving cream, etc. --- unless you don't care about the longevity of the glove.
You can try using some neats foot oil or pure lanolin to help soften the leather, but don't use too much or the glove will get too heavy. Since true neats foot oil or lanolin are next to impossible to locate, I use Lexol leather conditioner. You can get it from a shoeshine shop or online.
For future reference, always have two gloves if you are a catcher --- one for "game" use and one you're breaking in for next year's game use. I know it's expensive but it's one of the prices you pay as a catcher.
Also, I love the Akadema Praying Mantis catcher's glove, mainly because the thumb pad has a break in it that 1. creates a larger natural pocket and 2. prevents thumb injuries. So you might want to check it out the next time you're buying.