How long is the process for an IPO through an Investment Bank?

I am a novice in Finance,and is trying to raise capital for upcoming IPO. As I am a non-accredited investor I would like to know how much time does it take for an investor to raise capital through investment bank under regulation D.
What are the particular things to be prepared by me before contacting them supposing I have already discussed it with people who are making PPM.

1. An IPO is an Initial Public Offering, in which shares are registered with the SEC. Regulation D is a set of exemptions from registration that allow private offerings. The two are not the same thing.

It sounds like your company is trying to go through an investment bank to raise funds, and the investment bank is creating a private placement offering. If true, then you do not have an IPO.

1. It's unclear where your company is located. Are you in the US?
2. I'd strongly advise against using an investment bank to fund raise if you are an early-stage company in the US. You need to develop relationships with venture and angel investors and sell your company to them directly. They shouldn't need a PPM, which can cost tens of thousands of dollars to produce. If you're outside of the US, then there's a very good chance that whoever is producing the PPM and offering to fund raise for you in the US is disreputable.
3. In answer to your question, here's a form from the SEC with all the information you're supposed to provide to non-accredited investors: http://www.sec.gov/about/forms/form1-a.pdf