I suffer from piston slap so I tend to warm the car up completly before I drive her, so I can't hear the psitons clattering around.
I tend to sit in mine for 5-10 mins before driving so water and oil are just about right but as long as you dont spank it till it's warm you'll be ok. 5 mins at under 2.5k rpm gentle driving, Cooling down I normally drive off boost for the last couple of miles home then leave it stationary running for 30secs to a min. Subaru turbos are normally oil & water cooled so don't suffer the problems that oil only do, that necessitate a timer. At the end of the day it's prob a good thing to get used to doing so a turbo timer will do that for you if you cant be bothered to sit there and wait, personal preference really. If you do fit one don't tell your insurance company they dont like them [emoji52]