The first revelation was the opening five verses of Surah al-'Alaq: "Read in the name of your Lord who created" (Quran 96:1-5), which came to the Prophet (ﷺ) through Jibril in the cave of Hira when he was about forty years old. 'Aishah (may Allah be pleased with her) narrated the full account: revelation began with true dreams that came like the break of dawn, then the angel came and commanded him to read, after which he returned trembling to Khadijah (Sahih al-Bukhari 3; Sahih Muslim 160). Revelation then paused for a period (fatrat al-wahy) and resumed with "O you who covers himself, arise and warn" (Quran 74:1-5), as Jabir ibn 'Abdullah narrated (Sahih al-Bukhari 4). The scholars reconcile the two reports by saying al-'Alaq was the first revealed absolutely, while al-Muddaththir was the first revealed after the pause. This is a separate question from which surah was first revealed in full, and from which verse was revealed last.
Q&A · Quran
What was the first verse of the Quran to be revealed?
Evidence — the daleel
On deen2u
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.