Well, the title almost says it all, just got back from a few days out of town. When I got back and started my 2012 Volvo s60 it had this knocking sound at a cold start it goes away at 1000 rpm. If I accelerate it comes back, I haven't tried moving it. I talked to a few people and they say it's a lifter, so I'm gonna take the valve cover off and check it right now. I just wanted to get this out in case it isn't.

 

your car doesn't have a "valve cover" per se, just a dust cover. Replacing a lifter is a major effort - essentially its the same as doing a valve job. I would agree with the lifter noise assessment, particularly if its a regular ticking that changes pitch with engine speed. It should go away one the engine warms up. Have you checked oil level and color? Some 2012s S60s develop an oil consumption issue due to rings/pistons (google for the related service bulletins) so it may be down a few quarts :-(