Yes. Act 2 of every zone in sonic 3, except for AIZ and ICZ, starts either the second the end-of-level text appears, or the second the transparent title card appears. Angel Island Zone Act 2 starts when the midway boss sets everything ablaze. Even though the title card says Angel Island Zone Act 1 until you defeat the Act 1 boss. Ice Cap Zone Act 2 starts when you go through the tunnel on the way to the Act 1 boss (for sonic and tails) as stated before. It happens as soon as that block of ice slams down behind sonic and tails.