Hi Valerie,
This really depends on how serious and dedicated you are. Please read my post
How To Get A Flat Belly Quickly and Easily - 5 Musts from the link
http://www.healthcentral.com/diet-exercise/c/58426/52653/flat-quickly/?ic=4027 make sure you do all 5 religiously.
It usually takes about 12 weeks to dramatically change your physique, some can do it faster but 12 weeks of commitment is generally a good benchmark.
My advice is make sure this is a life long passion that you want to keep yourself healthy, fit and lean.
Health and Happiness
Kenn Kihiu
www.dancexfitness.com