I didn't mean to imply that you were pulling the wool over anyone's eyes. I simply meant that instead of approaching the question from the perspective of a CFI; approach it from the perspective of the customer. Instead of asking, "How much time would it take before you would feel comfortable giving tail wheel instruction?" why not ask yourself, "When I go get my TW endorsement, how much TW time would I want my CFI to have?" My suggestion was just to say that you can probably answer your own question if you consider the other side of the issue. Don’t be the CFI that you wouldn’t hire for yourself, your wife, your son, etc.
FWIW, I got my TW endorsement last summer. I wouldn't recommend anyone come to me to get theirs, although I could legally provide the training. They guy who taught me has thousands of hours of TW time and has flown them all his life. He teaches acrobatics and upset training and is nationally recognized within those communities. That was enough experience for me to sign up with him, but I don't know exactly how much would be the minimum I would’ve accepted. If he had said his TW endorsement was less than 2 yrs old or had less than 200 hrs of TW time I probably would have looked elsewhere.
Personally, it would take me several hundred hours before I felt comfortable enough to teach TW endorsements. If I was going to provide TW training, I would probably need to either buy a TW airplane to fly around for a year or more, or get a job in a TW towing gliders or banners or something before I ever thought about teaching in one. That answer is based on my philosophy that CFIs should have a broad experience base. When I got my CFI I had about 800 hrs PIC with ~500 of that being cross-country. As I started teaching, I was able to draw from that experience to help my students understand how the different aspects of aviation fit together and why the skill we were working on during a particular lesson was important and how it fit into the bigger picture. I have “Never Again” examples from my own experience that I use to reinforce points. In contrast, I went to ATP for my MEI/CFII tickets and my instructor there also had about 800 hrs at the time, and he had been a full-time CFI for about 10 months. He knew the gouge and could recite the FAR chapter and verse, but he didn’t have the broad experience I had when I had 800 hours. He went to ER to study aviation then got hired by ATP upon graduation, but had never taken a pleasure flight in his life. All he knew was the flight instruction environment, which isn’t the same as the world a pilot faces after leaving the protection of his CFI and venturing out on his own with a wet ticket/endorsement in his pocket.
I guess that was a long-winded way of answering your original question: minimum of 2 yrs and 200 hrs TW experience.