It depends on what you were trying to add and how much information you added. Have you used this guide?:
https://mydramalist.com/discussions/support/17285-guidelines-editing-and-submitting-new-dramas-movies-and-actors
When I tried it last time, it took about a day. They need to check the sources if it is a valid drama and if the information you sent is correct, do some editting if not everything is right (image I sent was replaced with some better) etc.
I don't know how it works exactly, but if you followed the guide and added links to sources of the information you sent then there is high chance that someone still works on it (otherwise you would get a message why it was rejected).
This is how I understand it as a common member. :)