Considering oaking secondary, how long?

Chips have a very large surface area. Soaking on them is a "weeks" level of effort. For my money though, you're better off using oak "cubes" which have less surface area and a better flavor profile to me.

 

Chips do 'work' faster than cubes.

My chips are soaked in 'enough bourbon to cover' for a week with a spalsh more bourbon added to cover again. Chips _and_ bourbon are added to the 2ndary for a week before bottling.

Some advise letting the chips rest in the 2ndary and tasting occasionally until the moment is right.
When dialing into teh oak...a little less is more better than overstaying their welcome.

 

I've done a couple of bourbon / oak brews. Usually it's been in the order of a couple weeks. (working with 5 gallons, chips soaked in bourbon for as long as I can - usually a couple weeks there too)
I've been happy with most, though I had one that used oak dust that came out way too strong, and a cider that was on for over a month with very little oakiness there.
I plan to try oaking again soon, and will be try cubes as well as chips, and varying the bourbon used.
The one I was happiest with was a Bourbon aged Dubbel. I had that one in primary for 3 weeks, then split the batch. Half went straight into bottles, the other half to another carboy with an ounce of chips that had soaked in Jim Beam for those 3 weeks. I left it there for 2 more weeks, and ended up with just the right balance of the original Dubbel maltiness / fruitiness, the bourbon sweetness and the oak astringency.
Again, it comes down to sampling occasionally. If you area planning on oaking a full batch, I'd start with 1.5 - 2 oz of chips. If you are looking for the liquor essence, soak in whatever you want. If you're looking for just the oak, either vodka (to sanitize them without adding flavor) or toss the chips in boiling water for a few minutes (alternative is to steam them for a while as well [don't know specifics of that; google it]) Let the brew go through primary fermentation. Transferring to secondary is optional; there are arguments on both sides of that one. Toss the chips (or cubes) in and forget about it for a week or so. Sample every couple days until you're happy with the flavors you get. Bottle or keg as usual.

 

Cubes for a long period of time. ~0.5 - 1 oz per 5 gallons for several months gives a nice integrated wood character that doesn't smack you in the face.