Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 7 · Samskara Muhurtas
संस्कारमुहूर्ताः
इष्टैर्जीवार्कचंद्राद्यैः पंचभिर्बलिभिर्ग्रहै ।स्थानादिबलसंपूर्णैश्चतुर्भिर्वा शुभान्वितैः ॥ ३७१ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 371.
Do it with five strong, favourable planets, like Jupiter, the Sun and the Moon. Or with four that are full of strength of place and the rest, joined by good planets.
Simple meaning: Five strong planets are best. Four strong, well-placed ones also work.
ईक्षन्नैवात्रैकविंशमहादोषविवर्जिते ।
Choose a time free of the twenty-one great faults. Any sign is good with good planets joining or looking.
शुभनवांशकगता ग्राह्यास्ते शुभराशयः ।
Take signs in a good navamsha. Never take a Cancer navamsha, even with good planets looking.
तस्माद्गोमिथुनांशाश्च तुलाकन्यांशकाः शुभाः ।
Taurus, Gemini, Libra and Virgo navamshas are good for the thread ceremony.