If you used an attorney, a quick call to him/her will provide you with the answer. If not, there are several ways. If you have the original notice of bankrutpcy filing, which was mailed to you right after you filed the case, you can find the filing date towards the top of this form. If you don't have any paperwork, then you will want to go to pacer at http://www.pacer.gov/findcase.html and look up your case. There may be a small charge for this.