cloning is and can be done at any stage or time of life as long as the plant is healthy enough to cut on.. that being said the more you clone a plant in veg the stronger the plant will become..cloning a single plant will only give you the genetics of that plant..this is why its called a mother plant..now if you take a clone from the original plant then take that clone and veg it out and clone it then you have a second generation plant and so forth and so on.. but the ever so popular question is as long as the plant is healthy then you and the clones are ok to do what you need..even in flower they can be cloned..it just takes longer to root..KEEP ON GROWIN