I just flew CTU-JZH-CTU on CA last week. The flights were on time both ways; this route is operated on a CTU-based A319, so chances of a delay on a morning flight is low, unless there's fog in JZH, in which case you may end up with multi-hour delays, so even building a few hour buffer won't help. I'd conclude that JZH-CTU delay is low risk, but high damage, if it happens. I had been monitoring the flight on flightradar for weeks and this seemed to be the pattern.

CTU-PEK on the hand, really depends on PEK airspace, which can be closed on the airforce's whim. I really try not to connect in PEK on evening flights unless it's on the same airline. Mornings/early afternoons are usually better.

I'm sure you're aware of this: JZH is about a 2 hour drive from the entrance of Jiuzhaigou. It's closer to Huanglong.