Yea, for sure don't idle longer than necessary. You probably don't need to idle at all, actually. Trouble is that oil pressure is at its lowest at idle and you'll be wearing engine parts fastest that way. Notice that in your manual it probably defines long periods of idling as "harsh" (or similar term) conditions meritorious of more frequent oil changes.
Mechanics worth their salt will suggest that you just drive very easy for the first few minutes 'till the engine warms up.
In some countries (European) it is illegal to leave your car idling to warm up. If the IS has an oil gauge notice that oil pressure is at its lowest at idle.
The M5 has a red (yellow?) line on the tach that gets higher and higher as the car warms up from a cold start. Hey, you can always run Slik50 or similar protectant if you're worried about longevity. As if any of us will still be driving our cars after say 50,000 miles, anyways!
Then again, 'other' Acura TL owners unlike myself might suggest that you rev the IS300 up to redline for a minute right after you start it up. That would be an easy way to reduce your compression ratio for a future turbo install...
------------------
'01 Acura 3.2TL
'88 Mazda RX-7 Convertible