Q: Had valve job done on my 2010 Nissan Titan and head gasket and valve cover gasket replaced, truck still puffs could of smoke

If you have not already done so, replace the PCV valve. You should have the engine compression tested to see if any one cylinder is low on compression. The cause of white smoke that is not just condensation in the exhaust is caused by oil that is in one of the cylinders and is put out the exhaust at startup and may be caused by oil control rings or by a leaking valve seal or by a blocked PCV valve. Try to run a decarbonizer through the intake and in fuel tank to see if the rings are sticking. Also i would try adding an oil cleaner like Marvel Mystery oil in crankcase to replace one quart of oil and this will clean and help unstick oil control rings. If none of this helps then seek a mechanic like one from YourMechanic to continue diagnosis for you.