Hi,
The regulations related to IPO issue can be found with the Stock Market Regulator, that is, SEBI. There are many things. Have you come out with a prospectus? If you have, then either you have your quantum of shares and issue price fixed or only quantum of shares fixed and you are looking to fixing the issue price based on book building process. Here's a link of BSE that talks a bit about book building.
http://www.bseindia.com/bookbuilding/about.asp
I am not exactly sure about the time factor, but I am guessing there is one. Have you appointed a Merchant Banker? IPO process requires one. If there is a Merchant Banker in place, then he/she would be guiding you through the process. He/she is the Wizard that will answer your queries.
Regards,
Vinisha.
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