I found the answer on the CIC web;0 M: Q l# n1 Z* T- b. @
"The certificate must have been issued no more than three months before you submit your application"% w: X Q6 T4 A& O2 x1 C6 l# [
( ~. s. v* j& J1 ~7 @Ours were more than one year when we applied.