@Michael.Liesenfelt did some calculations a few days ago:
What I would take from it: Pledge doesn’t make a difference until you have tens of millions of ADA that you can pledge.
Until then it’s just a signal for your potential delegators that you put your own funds into it. But it does not give you relevant advantages in return.
Also always keep in mind that you won’t get regular block production with less than around 1 million stake and you won’t be able to offer competitive rewards to your delegators with less than around 10 million stake.
The latter might change if the parameters are tweaked. The former will probably not change.