Not having read much on the subject (ahem!) I can only have recourse to my intuition, which is that celibacy was honored from apostolic times, but practiced only informally and irregularly at least in the ante-Nicene period. Certainly I suspect it was regarded universally as the ideal. How many of the Fathers were married?
Askel, it's not as though I lack for stuff to read, but I would like to get my hands on that book. But mailing it across town seems needlessly stand-offish, even for you. Besides, I'm holding your issues of Inside the Vatican, remember? For pete's sake, let's just pick a convenient time and effect a swap.