AIUI, you can only land as a settler once (i.e. you can't do your goods accompanying now and the goods to follow later, you do them both at the same time - I asked the same question - happy for someone to contradict if I have this wrong!).
AND (again AIUI) you have to 'land as settler' within one year or landing to declare PR.
I suggest that you land as PR on your planned trip and land as settler with your customs stuff when you are ready to ship, as the shipper will have to prepare a list of what they have packed.
Having said all of this, there have been stories that if you get the wrong immigration guy, they will INSIST they you have to do the customs stuff on your PR trip (you don't, but the level of knowledge and training of CBSA staff is, shall we say, variable!). So just in case, I will have my customs lists with me (yes, including our best guess at 'goods to follow').
So I personally plan to land with my wife (she is the PA) to activate her PR status in April 2017, then return to the UK to finalise the sale of our house here, hopefully by summer and then land finally as 'settler' with the customs forms in summer 2017 - hence I have looked into this in some detail.
