This would depend on a lot of factors. The manner that you would be monetizing your hub, the topic of your hub, the quality of the content in the hub, the volume of traffic that you attract, and the conversion rate of the traffic are but among the many factors. Looking into these may help a hub with an intention of earning money attain some success. I know of some hubs riding on the popularity of a certain keyword immediately earn a decent income even if their content left much to be desired. I suggest that hubbers who intend to earn money with their hubs read the many hubpages dedicated to the topic. Also, the Success Stories in HubPages would serve as an inspiration. Follow these hubbers and send them a message for some tips and advice. They might just reply to share a nugget or two.