The Alfa manuals sez to loosen each head nut at most 1/4 turn, oil washer underneath and torque to the specified setting. You do One nut at a time.
Bruce
"NEVER loosen the bolts before you torque them. This is not a good idea. This will cause damage to the head gasket which is already compressed and not in favor of recompressing (HKS headgaskets are, but stocks aren't). Besides that, it screws up the whole torque order, so you will put too much stress on the head as well!"