Well there is no official date, it has been a build up of sly remarks and abusive videos for the Past 2-3 years. Lil Kym feels that Nicki is just an imitation of herself and is copying everything Kim has already done before her. Nicki has said in previous interviews that she has nothing but respect for her, however as time has gone on she has retaliated on various interviews and videos.
Possible motives are the fact that Diddy mentored both little Kim and Nicki (Kim first).
Nicki posted for a photo in the same pose as Lil Kym.
Not to mention the numerous videos all over Youtube dissing one another. Here are two of the most blatant.
Nicki's Diss to Lil Kim
Lil Kim's Diss to Nicki
And why has all this been brought up we hear you ask? Well recently Nicki created a song entitled 'Stupid Hoe' this was supposedly a direct attack on Lil Kim, and has not gone down well with her or the public as it has twice as many dislikes than likes. Lil Kim was featured on 'Watch What Happens Live' and had this to say in retaliation.
“I’m pretty sure I feel the same way everybody else feels right about now,” she began. “If you have to make a song called ‘Stupid Hoe,’ you must be a stupid ho.”
Personally we have heard it all before and it just seems to be dragging on, the worst thing is that they both have such talent and it is being wasted on each other.