Depends a bit on the character. Some tripels, especially of more recent American production, are more hop-focused. If you take a month to oak it, you will lose out on some of your freshest hop aroma and flavor. Probably, though, you are fine in this regard. So just consider whether the vanilla and tannin are going to enhance the beer or detract from it.
In your position, I would probably bottle half of it and oak the other half. (How's that for a non-decision?)
The usual rule is that the oak should take about a month to infuse. Less time will mean less character; more time won't make much difference. If you have chips, they're a little hard to predict because of erratic surface area. So start with less, which you can always amp up if you think you don't have enough character.
