Today, 28 July 2011, is Guru Pradosh, Pradosh vrat on Thursday (Guru vaar / Brihaspati vaar). It is even more auspicious as it falls in Shravan month to perform Shiva Puja on this day. Today’s Pradosh falls in Krishna Paksha of Ashada month as per Kannada, Telugu, Marathi and Gujarati calendar. And it falls in Krishna Paksha of Shravan month in North Indian Hindi calendar. The best time to perform Pradosh puja is 4.30 pm to 6 pm.
The next pradosh falls in August i.e. Shukla Paksha of Shravan month in all lunar Hindu calendars in India.
Here is the link to read Pradosha Ashtakam, a prayer to chant during Pradosh Vrat.