From the website:

Can I park on the street after the sweeper goes by?

You should only park on the street after the posted time on the street sweeping sign.  Even though you may have seen the sweeper go by once, it may need to go by for a second pass.  Also, the City's catch basin cleaning program is closely coordinated with monthly street sweeping in order to reduce additional parking disruptions, and that equipment may be scheduled during the same posted time period.