I probably play on your level (Prince/King) and my advice is that if there isn't a social policy you pre-planned being in your overall strategy, then skip the Oracle. On Prince/King, you very well can pick up both the NC and the Oracle at a fairly early point (without being beaten to the Oracle), even without delaying the NC; you can usually build the NC first, then still get Oracle. And the hit you take to military or whatever else at that level is not usually enough to permanently set you behind.
The question then becomes:
How big of a headache will winning be?
With an OCC strategy, at least there's no time lost in relation to pumping out settlers (since you won't have to), and often OCC is science/culture oriented (or geared to puppet other civs, which Oracle doesn't help you with).
If you plan on having other cities, though, it's going to be an uphill battle figuring out how to both keep happiness up as well as keep military up, seeing as how you've lost time that could have gone toward building workers, etc.
Only if you really need the SP, or are going CV from the get-go, should you take the Oracle. Even with a cultural victory, it's debatable, since an early boost in science means you're the first one to get a crack at later wonders.
My advice: NC all the way and skip Oracle, unless you're going cultural victory.