The two times I was there (including the closing party) and if my memory doesn't fail, he began later than scheduled, at about 10pm on the terrace after another techno DJ (Christian Varela, Jack de Marseilles, etc), till some minutes after midnight. At the closing party I believe he was even playing there at 0'30 (exceeding much time the closing time for the terrace).
Meanwhile another DJ (I suppose invited by Carl too or some resident of Space) was playing inside, by now this room was pretty crowded but most of the people were on the terrace. And some time after the terrace had been closed, Carl Cox played inside too. But not sure how much time because I wasn't there until the end.
In my opinion, even though the vibe on the terrace was great (everybody hopping, cheering...), I found Carl Cox's set boring and monotonous both nights. And liked more the DJs who played before, and the ones who were playing inside whilst Cox was on the terrace. But this is a very good value night for everyone who likes techno.