Here is an excerpt from the Cannabis Grow Bible related to cloning. It doesn't give you a specific time, however, if you are thinking about cloning it is worth the read.
"Any cannabis plant can be cloned once it has been grown to a
certain height. The best place to take a cutting for cloning is above a
node which has at least 2 nodes above it. The smallest cuttings on
average are 3" in length.
Once the cutting has been taken it is placed in the growing
medium and should form new roots over the next week to three weeks
depending.
Cloning straight to soil has a low success rate. Leaving clones
in water also has a low success rate. The best medium for cloning is
rockwool cubes or Oasis foam bricks.
Not only that but in order to increase your success rates with
cloning you may wish to purchase some rooting solutions such as
Clonex ($3) which can be bought from most grow shops.
Make sure that you use a clean instrument, or even better a
sterile instrument, when you make your cut. Take the cutting and dip
the cut area into the rooting solution before placing it in the medium.
Clones do not need much light to root. Try to avoid using the bigger
grow bulbs for cloning. A simple window with some outdoor light is
all that you will need for that clone to root. Many people use Fluro
lights for clones.
When the clone takes root in the rockwool you will see the
roots jut out from the sides of the cube. When this happens the clone is
best transferred to its new grow medium, which can be soil,
hydroponics or aeroponics.
This is the most successful way of producing clones on the
market today."
