Cold, I have it loose enough to barely see the end of the drive link when pulling hard, then after warmup, it loosens up so I re-tension.  When done you should loosen as the chain will tighten up again as it contracts......this was on a stihl or oregon website.
	
		
			
		
		
	
				
			 
	 
	 
 
		 
 
		 
 
		