Can I perform the aqiqah for myself now—knowing that it is obligatory—given that my father did not perform it when I was born and I am now 24 years old? And must I declare that it is my aqiqah? And what is its quantity in terms of sacrifices?

"The 'aqiqah (sacrificial offering for a newborn) is a Sunnah, not an obligation. If a father did not perform the 'aqiqah for his child, the child can perform it for himself after reaching puberty. For a male, its perfect form is two sheep, but the fundamental Sunnah is fulfilled with one sheep. There is no need to inform the invitees that it is an 'aqiqah; rather, it is sufficient to gather people for it or distribute it with the intention of 'aqiqah."