Rent a flat or a house in New York

The apartment market in NYC can be very difficult and competitive.
- 10 to 20 days is plenty of time to find a place, especially if you do research on the market ahead of time. Most good places are on the market for less than a week before they are rented.
- Most move-in dates will be on the first of the month.  Mid-month move-ins are uncommon but can be arranged if the prior tenant moves out early.
- You can find an apartment on your own (using websites or contacting building mgmt companies directly) or through a broker.  Some buildings are broker-only.  Expect to pay 1-month to 15% on a broker fee (occasionally there will be "no fee" brokers).
- http://streeteasy.com/nyc/rentals - This is probably the best site for finding rentals, because it let's you define a lot of criteria, plus see your results on the map.
- http://www.nybits.com/ - This is all no-fee apartments listed by the direct mgmt companies.  Another great way to find an apartment.
- You can use Craigslist (http://newyork.craigslist.org/cgi-bin/apartments.cgi) to find both fee and no-fee apartments. Be careful, though - Craigslist has a lot of "bait and switch".  Also, NEVER send any money through the mail to someone offering an apartment.  If you use common sense, it will be fine and you can find some good places.
- I would recommend using those sites to get a general feel for the market now.  Then the week before you're ready to look for a place, start to contact brokers and management companies to line up apartment viewings.
- Try to see at least 3 or 4 places before pulling the trigger on one that you like.  After you have a good feel for the market, you'll need to be quick because good places are rented quickly.  Unfortunately there's rarely time to go home and "sleep on it" before making a decision.

Good luck and use your gut to avoid sleazy brokers!