This was also discussed in my post in this very thread and a couple of the replies around that same time.
The other big variable is that the current shipping estimates appear to be based on approximately 500 fulfilments/month. It is a possibility that this rate will increase or decrease based on many variables, some of which are beyond Purisms control.
Being as these estimates were just released I think it is reasonable to wait and see if the provided estimates prove accurate; something purism has a shaky historical track record on from what I’ve seen, but also something that they currently appear to be making a good faith effort to improve.
I hope that the currently set expectations are exceeded (or at least met); I won’t do more than hope at this point, but I do hope.
I also hope that if these estimates appear to become untenable because of supply chain issues (or any other issues) purism speaks up sooner rather than holding off and hoping things improve then making a last minute announcement (as appears to have been the historical method).