The decanting topic got done to death a while back:
http://forum.auswine.com.au/viewtopic.p ... =decanting
http://forum.auswine.com.au/viewtopic.p ... =decanting
I don't remember any particular conclusion (Mike/KMP will probably summarise
), but here is what I do:
Older reds with sediment are decanted within an hour or so of drinking, it depends more on the likelihood of crust than age for those less than about 8 yo, some 98's and 96's I'll decant, some I won't bother, older than that I nearly always decant soon before drinking.
For younger reds it depends on the particular wine, not just the vintage. If I'm going to drink a bottle of a big, possibly closed/reticent young shiraz or cabernet to try to assess it for purchase/cellaring I'll usually give it a vigorous decant an hour or two before the meal/tasting and see how it develops from there, often leave some in a half-bottle to the next day.
I seldom decant any wine more than 2-3 hours before consuming, if a young red is still reticent or a little stinky after an hour or so I will pour it quickly into another decanter and/or give it a good shake to aerate a bit more.
If I'm taking wine to a restaurant, wherever possible I double-decant just before leaving, to check for faults/suitability of the wine as well as avoiding the sediment.
On my last visit to Rockford in May (with Ric and John D), Ian the Stonewall CD manager decanted a bottle of 91 BP Shiraz by up-ending it into a decanter and then pouring it back into the rinsed bottle through a fine metal mesh - an example of applying the theory that removing all the sediment removes some of the flavour/character of a wine too. The wine did show pretty well after this treatment, we took the remainder to dinner about 6-7 hours later as well and it was in fine form. See here for details in TORB's tour diary:
http://www.torbwine.com/pf/SA%202005%20 ... er%204.htm