Got to this page, and click on the pdf marked "List of furnished houses and flats for rent", most of these places are available by the week or month. Hopefully you'll then find something temporary.

Normal time-frame to find a permanent apartment is 2-6 weeks. Lots of work and/or luck is involved. Here's a brief overview:
1. Get all of the paperwork that you'll need for an application (the rental agencies should be able to tell you what you need.
2. Call places as soon as they are advertised and schedule a viewing as quickly as possible.
3. If the place is at all decent, make an application.
4. Repeat steps #2 and #3 30+ times and you might be lucky.

If you have a job that pays you a huge amount of money then you may be able to repeat steps 2 and 3 fewer times, and you may be able to be more picky about which places you apply for. If one of your new colleagues is connected to someone in a rental agency in any way, then try to use this to your advantage. Apply for multiple places at the same time (a lot of the time, the agency will take one or more weeks to reach a decision).