I'm sure someone else will probably know more about this, but I know with my first appointment with the surgeon, he did an examination and said it had to come out anyway, so he was leaving the choice up to me as to whether or not to do a FNA. He did warn me it would be numerous sticks ( I guess because of the size of the nodule), so I decided to just wait and let them biopsy when they took it out to save the expense. Plus I had already it's not going to say 100 % for sure either way whether it's malignant or benign. However, the numbers are on our side :-)
I'm sure there are many factors that determine whether it's necessary to do an FNA, such as whether it will be a total removal of the thyroid or partial, for instance. I'll admit, it's hard to wait and I was tempted, but I figured since surgery was only two weeks away from when I met with him, I may as well wait. I dont' know how long after surgery one has to wait to hear the outcome of the biopsy though.
Good luck, hope it all turns out well for you! :-) Please keep us all posted on how things go...:-)