For you folks that went to tailwheels, how long did it take for you to get the endorsement? 1 day? 2 days?
Took me two days, 2.4 hours total. I also had a ton of glider time though, and gliders are almost all taildraggers. And I doubt many instructors would sign you off only seeing you fly once.
I don't know that you can really predict how long it will take though. There are really only three skills you need to master. Landing at full stall (a three point landing), landing on one or two of the main wheels (a wheel landing), and using the rudder. Most pilots prefer wheel landings (you have more control), unless there are operation reasons you can't (prop clearance and short fields basically). Using the rudder correctly is probably the hardest thing to master learning to fly a taildragger. Even harder if you are used to flying a 747 or an MD-11 - in my anecdotal experience, heavy jet drivers are not conditioned into making frequent rudder corrections.
The best way that I have heard it explained, a taildragger is like a kid's tricycle. Pushing it forwards, pretty easy. Now imagine grabbing the handle bars and pushing it backwards. If it moves off of the line you want it to move in even slightly, it will veer off in that direction quickly. The key to maintaining directional control in a taildragger is to make constant, small rudder corrections to keep the nose pointed where you want. You can't ignore this for a second. The consequences for screwing up can be pretty severe. The airplane may either leave the runway, flip over, or end up with the tail in front (a ground loop).
With trike gear, as long as you can put the aircraft in ground effect and keep the nose up, eventually you are going to touch down somewhat safely. Not so with a taildragger. To cause the main wheels to touch first, the airspeed must be well above stall speed. If the main wheels touch hard enough, they will bounce and increase the angle of attack, causing the aircraft to lift off again, and probably bounce again. To prevent this, two things are necessary. The rate of sink must be well controlled, and when the wheels touch, the stick needs to move forward to counter the additional angle of attack you are about to get. To control the rate of sink, you either need to adjust power, or flare with excess airspeed. All the while, you need to be dancing on the rudder pedals to maintain a straight track along the ground.
If you can, grab a copy of
Stick and Rudder and read through it before hand, it should make the techniques you are trying to learn more clear.