Hi,
I don't think it really matters which one you start with, so long as you prepare for each exam well, then just book in your exam and do it..
I'm studying at present for ops/performance and i've only got another few weeks to sit and pass that exam... Should have done it 3 yrs ago when I did the other 6!! hmmm, so maybe you should get that one out of the way 1st!...
Good Luck with them!