Is it considered a Bid‘ah (innovation in religion) to agree upon a specific time for a session of remembrance of Allah (Dhikr), and to raise one's voice in Dhikr, such as "Lā ilāha illallāh (There is no god but Allah)"?

Gathering for the remembrance of Allah Almighty is good, provided it does not become a regular habit and is not accompanied by an innovation (bid'ah); such as performing dhikr in a collective voice, or making appointments to gather specifically for it. Some scholars have disliked this, and Ibn Mas'ud (may Allah be pleased with him) censured a group of people who would gather in the mosque and remember Allah with a collective utterance.