Pheezer,
Most of the successful knifemakers out there, were part time for many years. That is not to say that you can not make a living making knives, Warren Osborne is an example of that.
Truth of the matter is that Warren is the exception not the rule.
Your best bet is to stay part time, till you have some experience. Generally 5-7 years, by then you should be a 6-12 months behind. Hopefully your equipment is paid for and you have enough materials to make knives for 6 months before you have to buy materials again.
I am a full time custom knife dealer. I was part time for 7 years before I went full time 5 years ago. Much like custom knife makers, many want to be dealers. But soon they find that it is not as easy as it looks (but nothing ever is).
I agree with Steve B. do take your wife's opion into your decision. Its much better to have her on your side. Remember if Mama ain't happy....ain't nobody happy!
Best of Luck.
Les