Question:

Is it allowed to perform an aqeeqah of a very young infant who only lived two or three days and died before the seventh day? What will its status be in the Shariah? Will it be sunnah, mustahab, jaaiz or impermissible? If it is permissible, which day should the aqeeqah be performed? Usually aqeeqah is made on the seventh day.

Answer:  حامدا ومصليا ومسلما
Aqeeah is mustahab. It is to be performed on the seventh day. Shaami writes:

 يُسْتَحَبُّ لِمَنْ وُلِدَ لَهُ وَلَدٌ أَنْ يُسَمِّيَهُ يَوْمَ أُسْبُوعِهِ وَيَحْلِقَ رَأْسَهُ وَيَتَصَدَّقَ عِنْدَ الْأَئِمَّةِ الثَّلَاثَةِ بِزِنَةِ شَعْرِهِ فِضَّةً أَوْ ذَهَبًا ثُمَّ يَعِقُّ عِنْدَ الْحَلْقِ عَقِيقَةً 

If a child dies in one or two days after birth, one may still perform an aqeeqah on his/her behalf. There is hope that Allah Ta’ala will accept it. (كتاب المجموع للنووي 8:448)

And Allah Ta’ala knows best.
(Hazrat Mufti) Ahmed Khanpuri (May Allah preserve him)
Mahoodul Fatawa 5/618