It takes as long as the longest part of your documents. For me, the longest part was from one certain country and if i had applied to that PCC and then the next day I applied for all other PCC, documents, transcripts, etc, I would have everything done by the time my first PCC arrives. Look at all your documentation and see which would take the longest.
I don't believe I had any documents that had to be done before doing anther document (i.e., in series), hence all could be done in parallel. Finally, when you deal with personnel at a company who are busy, the experience letters may come back wrong and then you may need to re-do them.
Good luck.
