Gold

[henry1938]

i often wonder how long does gold take to be gold

[woofgang]

Its an element. It has been gold since the elements were created.

[Bazile]

It doesn't take as long to make purest green

[EDDIE51]

It has been Gold since the Universe was created hundreds of billions of years ago.

[Baldric]

/// It is thought to have been produced in supernova nucleosynthesis and from the collision of neutron stars[4] and to have been present in the dust from which the Solar System formed///

https://en.wikipedia.org/wiki/Gold

[Bazile]

'hundreds of billions'
Crikey EDDIE51 - have we been going that long ?

[Old_Geezer]

Getting on for about 14 billion only it seems.

The original OP question isn't that clear. Surely the time between when something is one thing and being another is instantaneous. One instant it isn't defined as x the next it is. It's almost as if one is implying intent and wants to know how long the recipe took to make.