Avatar-based
     

Option #1

With this first option, the Na'vi baby has a functional consciousness and will develop into an independent individual with a mind of his or her own.  These may not be used for transplantation procedures.  This option is suitable if you wish to live alongside the Na'vi, but not actually become one.  

Option #2

With this second option, the Na'vi baby has no consciousness and will not develop independently.  Life support is not necessary, however, as the pons and medulla of the brain will still function for autonomic requirements of life.  Intravenous feeding will be necessary until transplantation occurs.  The transplantation will occur immediately after the baby stabilizes, which happens about ten months after artificial implantation of the zygote into the surrogate mother.  This option is suitable if you wish to become a Na'vi immediately, without waiting.  The Na'vi body does not reach the full height of three meters until about age twenty, however.  The suitable height of six feet to function in society occurs around age six.  

Option #3

This is exactly the same as Option #2, however the transplantation is delayed.  Instead of being transferred into the Na'vi body right away, you will wait for six years and allow the Na'vi body to partially develop.  This is optimal for immediate functioning in modern society, and is, by far, less risky.  The cranium would be completely developed, so it would be much safer to transplant the neocortex.  
     

Gene Therapy-based
     

Option #4

With this fourth option, your current body is modified to be a Na'vi body.  This is done chemically through gene therapy, likely to be done in vivo, meaning it would be periodic intravenous injections of a genetic vector.  However, a minor surgery is required in conjunction with the gene therapy, that being rhinoplasty (surgery of the nose).  The new genes cannot manifest in already-formed bone, therefore the change in nose structure must be accomplished surgically.  It may also be necessary for otoplasty (surgery of the ears), but this will not be known until more research is done.  

Note:  the number of fingers will not change.  Unlike true Na'vi, you will still have five digits on each appendage.  Also, the height cannot be greatly modified without extreme risk to the spine.  As a result, the gene therapy would probably only allow you to grow to a maximum of 1.93 meters (6 feet, 4 inches).  

In my opinion, this is the most promising option.