I think that sometimes people tend to forget that a year is twelve months long.
Plus, about that news which Eunjung rejected an offer to star on a SBS drama saying she wouldn't have time because of their promotions and the Asian tour CCM also stated:
Guessing their comeback promotions will take from them a month, plus a month of concerts in each country from that tour, I think there is still enough year for other activities
btw,
in Jiyeon's case postpone College, imo, is a smart decision since it is a responsibility that she will have to attend the whole year.