The few deciduous trees that we have in the lower elevations of So Cal usually don’t turn until mid-November.
Here’s a pic that includes some of the foliage about 22 miles northeast of Quebec, QC. It was taken on September 24 in 2007. Apparently there are only about 5 trees that even started to turn, so I’d say yours are definitely turning early.
I’d say that was nice, as long you still have most of your fall foliage on Halloween.