Why 20 months? I’m so glad you asked. Like most of Dickens' novels, it was originally published serially. This read along will be read in installments, similar to the manner in which the original readers had to wait anxiously for the next portion (two/three chapters). This month, March 2016 also marks the 180th anniversary of the first published installment, so this is in keeping with the original schedule. Please read more about this brilliant read along at the host site: On Bookes.