I can't help you on how long it's going to take, but there are a few simple things you can do that are naturally diuretic... any kind of green juice (especially celery) will help, and there are herbal teas (dandelion, fennel, yarrow etc.) that are mildly diuretic. It may get worse before it gets better, but increasing your water intake can help flush out your system too.
A lot of people will tell you to cut sodium, but a lot of smart primal thinkers think that's not true... I can probably find some links somewhere.