Hi fasting2goal, refeeding time should be equal to or greater than the length of the fast. Paul Bragg prefers to do 7-10 day fasts now and then, but a 20 day one should be fine.
For weight loss, I did around 7-10 days, and I could "feel" when I was ready for another fast, I guess this was when my body was fully restocked. Sometimes it was more than the recommended period, other times it may have been slightly less, but generally more.
Your refeeding schedule sounds perfect. Also, go for what you fancy, be it Watermelon, cherries or anything else.