P5 or SBL in Spetember 2018?

Hi
Just looking for advice.

I am thinking between:
option 1 – SBL in September and P5 in December, or
option 2 – P5 in September and SBL in December

Nobody did SBL yet and I understand its one big surprise, but based on the fact its merge of P1 and P3, should SBL be done before P5? Is there much of P3 knowledge required in P5?

Another thing is that I have a P5 books for exams until August 2018. Is it still suitable for the exams after September 2018? Anybody knows is there much change in P5 from one year to another. I was checking the syllabus and study guides on ACCA wabpage but last page is just blank.

Is it smart at all to attempt SBL in September not knowing what to expect?
I’ll have to do it one day anyway and maybe they won’t be so strict on the first round, but in the other hand, maybe I should wait until December to have better idea of what I’m facing?

Any advice greately appreciated.