I am part of a group who divide the Tehillim daily for Shidduchim for our children. We try to complete our portions before Shkia but sometimes some ladies do not finish it before Shkia. My son pointed out a letter from the Rebbe which seems to indicate that it is okay to say Tehillim until צאת הכוכבים and another letter which seems to indicate till Shkia. Is it okay to say till צאת or we should really try before Shkia?
The apparent inconsistency between the letters has been raised in several areas. (See also below). Practically, it depends on the situation. Ideally, it should be done before Shkiah, but…