Is it permissible to divide the 'Aqiqah over two days, or must it be offered all at once?

The 'Aqiqah is the animal sacrificed for the newborn on the seventh day. It is a confirmed Sunnah. The Sunnah of 'Aqiqah is two sheep for a boy and one sheep for a girl. It is best to slaughter them both on the seventh day. There is no objection to slaughtering one of the two sheep on the seventh day and the other later, or distributing the 'Aqiqah over different days.