Hi @dpb,
I tested, and the post count isn’t updated in real-time.
My guess is that there’s a Sidekiq job that takes care of that periodically, but I don’t know which one.
It doesn’t seem there’s a specific related Sidekiq job 
But I read that this stat is updated at least once a day.
A GET request to https://your-discourse.org/u/username.json will return the right number, though.
If you want a reliable number, make such a request after receiving the webhook payload.