Hi there,
Ive just been to the vet this week for my 8 yr old boy, Mo, for conjunctivitis too. Hes had it quite afew times, and i generally find that once we start applying the ointment given by the vet, it takes about 3-4 days before there is an improvement.
If there is improvement after a week, i would take them back to the vet though, as i was told by my vet that it could signify a problem with the cornea if theres no improvement. Hope this helps!