Does anyone know what exact day in the book "Angels and Demons", the Illuminati carry out the Vatican event?

Anyone, anyone!?

"Robert Langdon wandered barefoot through his deserted Massachusetts Victorian home and nursed his ritual insomnia remedy -- a mug of steaming Nestlé's Quik. The April moon filtered through the bay windows and played on the oriental carpets. Langdon's colleagues often joked that his place looked more like an anthropology museum than a home. His shelves were packed with religious artifacts from around the world -- an ekuaba from Ghana, a gold cross from Spain, a cycladic idol from the Aegean, and even a rare woven boccus from Borneo, a young warrior's symbol of perpetual youth."

found an excerpt!!!!

a hint...it's in April that the book starts....!