Where can I find the bus schedule from Chengdu to Jiuzhaigou and also for the way back?

You can take a bus to JZG from Xinnanmen Bus Station. The buses depart at 7:30, 7:35, 7:40, 7:50, 7:55, 8:00, 8:05, and 8:10. Also, you can take a bus to the scenic area from Chadianzi Bus Station. The buses are available from 6:10 to 19:10.
The return buses depart at 7:00, 7:05, 7:25, 7:30, 7:40, 7:50, 8:00, 8:10, 8:20, 8:50, and 9:30. The fare is CNY 137 or 152.

Does the bus still depart from Chadianzi at 19:10?

Yes, the bus departing at 19:10 from Chadianzi still exists. But the schedule is quite hot. I suggest you book it in advance if possible.