According to Dani Martinez, a journalist in Spain, Kristen and Charlize will be promoting ‘Snow White and the Huntsman’ in Madrid, May 17th. (probably correct, let's just watch out for this date)
Via Twitter, Universal Spain has confirmed Kristen and Charlize’s appearance for 'mid-May'. And states that they will be doing press but no premiere is currently scheduled.
DanielMMantilla/DaniMartinez El día que vienen a España Charlize Theron y Kristen Stewart a presentar su versión de Blancanieves es el 17 de mayo.
Twilight Poison #SWATH @Universal_Spain is confirming the visit of Kristen and Charlize for mid May. They ask you to stay tuned. However, they're not planning a premiere, so it might be just a press junket, photocalls, etc.