Here are a few other ways to say "first name" in Marathi:
* पहिल्या नावाचे (Pahilya Navaache): "of the first name"
* प्रथम नावाचे (Pratham Navaache): "of the first name"
* आघाडीचे नाव (Aghadiche Nav): "leading name"
You can also just say "नाव" (Nav) which simply means "name" but it will usually be understood as the first name in context.