Interesting to see AC leave T2A for T1 after so many years.
Last time AC operated out of T1 there was much less prior notice time for the move in the aftermath of the tragic T2E building collapse. The move happened overnight !
AC was at T1 from mid-June 2004 until just after the start of the 2005 New Year as described here:
Effective June 11: AC moves to T1 at CDG