I'd sample every few days as it seems like it can go from under to over oaked in a matter of days. Alternately you could add less chips to start, and just leave them in secondary longer.
Ok thanks Yooper & Vandulus I have a 6.6 gallon batch with a half lb of chips soaked in bourbon for 3 weeks prior to seconday.The stout has been on the chips for 5 days and I am anti pre tasting for several reasons should I keg or let ot go longer ?????? THANKS
Taste it to find out. There's really no other way to find out if it's enough. If you are dead-set on not tasting it, then keg it now and revise your recipe for the next time you make it.