Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 7 · Samskara Muhurtas
संस्कारमुहूर्ताः
सौम्यायने नास्तगयोः सुरारिसुरमन्त्रिणोः ।अपर्वरिक्तातिथिषु शुक्रेज्यज्ञेंदुवासरे ॥ ३३६ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 336.
Do it in the Sun's northward course. Venus and Jupiter should not have set. Avoid a parva (junction day) and empty tithis (moon days). Use Friday, Thursday, Wednesday or Monday.
Simple meaning: Do it in the Sun's northward course, on a Monday, Wednesday, Thursday or Friday.
दस्रादितीज्यचंद्रेन्द्रपूषभानि शुभानि च ।
Good stars for a first haircut: Ashvini, Punarvasu, Pushya, Mrigashira, Jyeshtha, Revati, Hasta, Chitra, Swati, Shravana, Dhanishta, Shatabhisha.
पट्टबंधनचौलान्नप्राशने चोपनायने ।
The birth star is good for these four rites and bad for other rites.
अष्टमे शुद्धिसंयुक्ते शुभलग्ने शुभांशके ।
A clean 8th house, a good rising sign, and the Moon away from the 8th, 6th and 12th help this rite.