How to take a bus or train from Xian to the Peak in Jiuzhaigou around Oct.11?

You can take bus from Sanfuwan Bus Station and arrive at Guangyuan Bus Station first. The bus schedules are 08:10 and 16:10. It costs CNY 140 per person. After arriving, take a coach to JZG. I remember that they depart at 06:00 and 10:20. The ticket fare is CNY 92 or CNY 106. Then take a bus or hire a private car to the scenic area. :)

how long is the journey by bus from Xian? Thanks

Well, it takes about 8 hours to reach Guangyuan, and another 5 to 6 hours to reach JZG. ;)