General information.
Most likely you will submit a utility patent. This must be novel, nonobvious, and useful.
The US is now first to file, no longer first to invent.
Software patents are difficult to obtain.
A prior art search is done before you submit for a patent.
You have one year to file if you have made your invention for sale, or publicly disclosed it without an NDA.
You can file for a nonprovisional which gives you one more year to file your provisional filing.
I am not aware of your situation, so I would suggest watching the IP video provided by the US patent office, look at the following link, and contact a patent attorney for a 1 hour consultation.
http://www.uspto.gov/patents-getting-started/general-informa...
Have you filed a patent in the past (I assume so)? Do you have any idea how long does it take from submission to obtaining a response?
* a prior art search is not required (that's the PTO's job) but i usually recommend it since it'll save money in the end if there's dead on prior art. it's also required if you want to expedite the process at the PTO.
* you can file for a provisional first then have a year to file a non-provisional based off that.
on your follow up: the time process varies wildly but its in the years time scale (not months or shorter). anecdotally i just gave the PTO a call regarding an application that has been sitting around waiting for an initial response for 2.5 years now, which is somewhat uncommon but not out of the realm of possibility. you can speed up the process, but the PTO charges a rather hefty fee for it.
disclaimer: i AM a patent attorney (and former examiner), but i'm not your attorney!