Approximately the same time as it has taken the original to arrive at the same age and physical condition, obviously!
Yet this may not quite be acceptable from a plot point of view, so here's a few pointers on reducing that time frame, contingent on the use of the clone.
Spare parts
You don't actually need a full clone for this, it should be possible to graft the organ to be replaced onto a bio-compatible host and with growth/rate accelerators you'd be looking at several months to years. Some organs are problematic: the brain, for instance (we simply don't know enough about the interconnections between all the neurons except that these interconnections are partly created through learning by the individual), but also muscles as muscles need a work out to be compatible with the individual receiving the spare part. On the bright side, you can require some re-validation therapy and it may be advantageous to use a younger version of an organ.
Rejuvenation
The practice where a much younger clone is used as a replacement body when old age becomes a hindrance. This requires a mind transfer technology which presumably fixes the neuron and neuron interconnection problem. There is plenty of time to grow a body (say, twenty years) and the clone body does not need much exercise and can be kept unconscious during the entire growth cycle. A period of up to a year of exercising the new body after the mind transfer (the old mind has to adapt to the much younger body) is probably acceptable as well.
Replacement
The practice where a clone body is offered as a replacement in case of accidents or after being murdered. 335
Again, this requires a mind transfer technology in addition to regular mind recordings as a backup to restore onto the blank slate. This is one of the more difficult use cases as it requires the body to be grown fairly fast, say less than five years, while keeping it a blank slate. Another problem is to copy the physiological impact of the environment on the new body, i.e. scars, wear and tear, and so on. Without this the clone will not have an identical or even similar look! Again an adjustment period of the recorded mind to the new body of a year is acceptable.
Replication
This is the use case where the genotype of successful individuals are copied to augment (or supplant, whatever the plot is) the general population. The problem here is to copy the environment and learning processes too as the phenotype is the determinant of success, not the genotype on its own. However, decades to grow and learn a clone into an individual are permissible, as each copy will be an individual, albeit very similar to another copy.
Other uses
There are probably other very creative uses of clones but the main things to consider are:
* in how far does the phenotype (result of environment and genetics) of the clone need to match the original? A blank slate is much easier than a fully trained individual.
* how much time do you have to prepare the clone in advance? If you need anything less than a couple of years, I'd seriously look into biological 3D printing and infusing the 3d printed cells with the DNA from the host. 335