I plan to start the Solstice Challenge with a light day, particularly because yesterday was not light (!).
We had been invited out for both lunch and dinner, and I knew that there would be a LOT of food at lunchtime. I am actually quite pleased with how I managed the food at lunch, only having small serves of each of the courses (couldn't really refuse a course, as different people had made each course and it would have seemed rude). I drank very little alcohol, which also helped. Dinner was a far smaller affair, food wise.
However, given that most of the foods were calorie dense, I did eat more than my body needed. This should mean that fasting until later in the day is doable!!
Good luck and best wishes to other Monday fasters and for the start of the challenge!