So I am new to pathfinder so take this with a grain of salt... But I haven't found any rule that lets you split up the +2 ability boost into two +1's. It really made me feel like I was wasting a boost just to get from a 17 score to an 18 score.
Maybe other people disagree with me..... or maybe I misread the book somewhere....but I think you should allow some easy way to get those odd number skills to even number ones, for us min/maxers out there lol
I guess the first question would be, how did you get a 17 to begin with?
If you're using the new method for generating ability scores, you should only get even results (at least until you start raising stats past 18 at 5th level).
If you used the optional method to roll for stats on page 21, then the rules there say that if you have a 17 then you can either leave it at 17 for now or use the boost and only get it up to 18. I can see why that might feel a bit disheartening, but they don't want any characters starting above an 18 at 1st level.
Of course, if your GM is cool with their players splitting a boost like that, that's their call.