Here is Alex Irvine, author of The "Supernatural" Book of Monsters, Spirits, Demons, and Ghouls and John Winchester's Journal, tentative appearances schedule for the next few months:
May 15: Smartish Pace/Barrelhouse Launch Party, Baltimore MD
May 17: Maine Comics Arts Festival, Portland ME
July 11: Books & Blooms, Boothbay ME
July 23-26: San Diego Comic-Con
September 19-20: BangPop!, Bangor ME
October 3: Bangor Book Festival, Bangor ME
Source: Alex Irvine Blog.