[pubsubhubbub] Where do I set the time of blog notification to subscribers?

[Sharon Jackson]

Several months ago, I installed hubbub, not realizing precisely what it 
does. Even though the blog is set to publish immediately, in fact, the 
notifications do not go out to subscribers until 3:30 a.m. This does not 
work for late breaking news. Can someone tell me where I can change this?