Starting a photoperiod plant this late in the grow season will likely to produce low yields. If your plant will get 8+ hours of direct sunlight and you give her water-soluble nutrients (as waiting for compost or other slow-release nutrients might further delay growth) you might get something. I started mid-July my first year and results were poor, keep in mind that was my first grow, so I didn't know much.
Hope this helps and good luck!