Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 7 · Samskara Muhurtas
संस्कारमुहूर्ताः
वैशाषे धनवान्वेदशास्त्रविद्याविशारदः ।उपनीतो बलाढ्यश्च ज्येष्ठे विधिविदां वरः ॥ ३५४ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 354.
In Vaishakha, he becomes wealthy and skilled in the Veda, the sciences and learning. If the thread rite is done in Jyeshtha, he is strong and the best of those who know the rules.
Simple meaning: A thread rite in Vaishakha brings wealth and learning. In Jyeshtha it brings strength and skill in rites.
शुक्लपक्षे द्वितीया च तृतीया पंचमी तथा ।
For the thread ceremony, choose the 2nd, 3rd, 5th, 7th, 10th or 13th day of the bright half.
श्रेष्ठा त्वेकादशी षष्ठी द्वादश्यन्यास्तु मध्यमाः ।
The 11th, 6th and 12th days are best. In the dark half, only the 2nd, 3rd and 5th are fine.
धिष्णान्यर्कत्रयांतेज्यरुद्रादित्युत्तराणि च ।
For the thread rite, good stars include Hasta, Revati, Pushya, Punarvasu, Shravana, Ashvini, Anuradha and Rohini.