I wouldnt pin the Sust as you would pin the Enanthate. Thats a waste of Propionate, as minimal as it is. Pin it every other day. Adjust eod doses so at the end of the week you = 500mg.
If you have a mixed estered product such as Sustanon you want to base your injection protocol on the shortest ester in the mix. In Sustanons case the shortest ester is the Propionate. Propionate should be pinned every other day or AT LEAST mon, wed, fri.
150mg eod=525mg per week.
For PCT I would wait 30 days. Sustanon, if its not BS Sustanon, has the Decanoate ester in it, and that ester has a half life of 15 days. If you start PCT too soon you will most likely have a failed PCT as you have drugs still in your system that are telling your body to shut down as well as drugs telling your body to turn on. Starting PCT too soon is not what you want to do.
Switching over will be fine.