I lived in Tucson for 4 years and hiked the surrounding hills alot - never saw any wild tepins. I'm not sure exactly where they do grow, but I think you will need a more specific plan than to just go search around Tucson.
As for time of year, I'd guess september or october for the most pods - south AZ is cooler than Phoenix, but only by like 10-20 degrees. Otherwise maybe in the very near future before it gets too hot.