There are people who can date someone else while they still have an emotional attachment to an ex - personally I can say from experience that that's a bad idea. A woman I dated essentially wanted to turn me into a more acceptable version of her ex - down to the clothes and wearing a gold chain
There are also people who detach firmly, quickly and completely. I would suggest that most of the people who end up on forums like this aren't those sort of people. I know that it took me literally years for that. AND I thought I was ready to date at 6 months out. Got talked down from that.
Given my own set of circumstances I'm waffling around. For right now I have no interest in dating for any sort of intention. Prior to that I was dating with the intention of finding a new partner - and got burned badly - twice - in that experience.
I personally think that the more clearly you can have your own baggage categorized and taken care of with no distracting strings or emotions pulling you in unexpected directions the better you will be able to have a satisfying relationship of any sort.
On BD H52, W50 T27, M26 S21, D23 BD-9-Mar-16 D-15-Jan-18 Final-19-Apr-18 I am a storyteller. The story may do you no good. But a story is never for the listener. It is always for the one who tells