Rentals in Poway go quick. As you probably know, Poway offers a great community, close to the city and beaches, yet more affordable, and an award winning school district.
I would suggest when you find one you like, grab it. Most rentals in the area come on and off the market very quickly.
I have found craigslist to be the best resource for rentals in the Poway area. Of course, be diligent and research the property and the owner prior to signing contracts or exchanging money (there are scams out there). Also, the the rental looks to be to good to be true, know you didn't "find a deal", you more likely "found a scam".
Best of luck!