I home first and then set the G54 offset to the part. Said differently, the software is told where the tools cutting edge is located and I define to the software where the part to be machined is located. KISS!
That can be done a number of different ways and I use a custom screen to make it all simple.
I set up manually using probing to find the lathe center, the part, and tool offsets.
Now as Carrot Head once said.....it's not how you pick your nose but rather where you put your buggers that is important!
So home / reference / cutting edge of tool is Machine coordinate X&Z=0 and safely away from the end of the stock such that the longest tool offset clears the stock. The G54 offset is the distance from the cutting tools edge to the part.
RICH