You can receive visitors in single digit (0-9) and also you can have up to 4000 visitors to a single hub in a 4 days period. It all depends on the topic, nature or quality of hub. If your hub is addressing the problem of a large group and problem is of immediate concern, visitors will flock your hub like anything. However, this is most unusual pattern. Just ask few simple questions to yourself before clicking "publish now" button:
1. What is so unique about your hub that visitors will come to your page instead of finding better information on other sites?
2. Is your hub the only webpage that contains information no other site has on this topic?
3. Problem you intend to address in your hub is really a problem that making people worried at present?
4. Have you raised a voice against any injustice being done by an agency (Govt. or private) or a group?
These are few basic questions related to traffic besides technical issues like SEO.