Answer
Wa `alaykum As-Salamu waRahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
There is no merit or a reward or a statement from the Prophet to confirm that one should name his child according to the name of the day or the month.
Answering your question, Dr. Mohammad S. Alrahawan, Associate Professor at the department of Islamic Studies in English, Al-Azhar University, Egypt, states:
Etiquette of Naming a child in Islam
Naming a child is one of the duties laid on parents. According to the report of Samurah which was related by At-Tirmidhi, the Prophet Muhammad (peace be upon him) said; “A child is mortgaged by his `aqiqah. Slaughtering should be done for him on the seventh day. He should be given a name, and his head should be shaved.” The hadith is graded as authentic.
The default rule is that all names are permissible, but it is disliked that a person picks a bad name for his child.
The Prophet (PBUH) has been reported as changing some of his Companions names for this reason. He has been also reported as saying, “The names dearest to Allah are ‘Abdullah and ‘Abd al-Rahman.” (Muslim)
Naming a child according to the name of a day or a month
There is no merit or a reward or a statement of the Prophet to confirm that one should name his child according to the name of the day or the month. As long as we do not have authentic evidence from the Quran or Hadith to support this practice, it is a restriction of what Allah has made spacious and permissible for us. It may be labeled as an act of innovation if a person does it out of thinking that it is a meritorious act.
Allah Almighty knows best.