Hey Tom, hey Tom 
by the way, interesting:
T – Select Tool
Tx - prepare to change to tool x.
The tool is not changed until an M6 is programmed.
[…]
On some machines, the carousel will move when a T word is programmed, at the same time machining is occurring. On such machines, programming the T word several lines before a tool change will save time. A common programming practice for such machines is to put the T word for the next tool to be used on the line after a tool change. This maximizes the time available for the carousel to move.
I don’t know if someone in this forum has a cnc mill with tool carousel in their workshop, but I think some already worked on machines with one.