At the due moment (2,3,8,2,4)
I believe the answer is:
in the fullness of time
'at the due moment' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for in the fullness of time that I've seen before include "At the destined moment" , "At the due moment (2,3,8,2,4)" , "in due course" .)