My personal issue with its use is how easy some people fall back on it.
Like lenny faces.
Some edgelord wants to show the server what a bad ass he is, but can't put it into words, so he spams a bunch of racist shit or lenny faces into the chat.
Nibba is just the family friendly version, used by a person who can't think of anything witty to say, but still wants everyone to notice them.
But, that's just me.
EDIT: In regards to a time frame, I usually give my votes a week before acting. Give everyone who wishes to voice in a chance to do so.