It is narrated from Nafi' (may Allah have mercy on him) that Sayyiduna Ibn Umar (may Allah be pleased with them both) used to cut his nails after fifteen days, and shave the hair below the navel after one month.
Hadith Referenceالادب المفرد / كتاب الختان / 1258
Hadith Gradingالألبانی:صحيح الإسناد موقوفًا
Hadith Takhrij«صحيح الإسناد موقوفًا : أخرجه الخطيب فى الجامع لأخلاق : 862»
Explanation & Benefits
Shaykh Maulana Usman Muneeb
Benefits and Issues: This does not mean that it cannot be done earlier. The meaning is that this was the practice of Sayyiduna Ibn Umar radi Allahu anhuma. If there is a need felt before this, then it is permissible.
Source: Fadlullah al-Ahad: Urdu Commentary on al-Adab al-Mufrad, Page: 1258