FD10 is my "standard" film developer. Much along the lines of what Tom says, I find that maintaining the temperature is important and the times quoted (in notes so small that you need a microscope!) are a little optimistic. I normally give a couple of minutes longer than the recommended times for my usual FP4 and I suspect you'd have to go a long way to end up with overdevelopment. I normally pre-soak, but the original reason for doing so was that my darkroom (where the loaded tank/film will have been) and kitchen (where I develop) are both unheated, so in the depths of winter it helps to get the film and tank up to temperature so they don't have a cooling effect on the developer. Keeping properties of FD10 are excellent and a major selling point for me. Exclude the air by squishing the bottle and /or throwing in air balls and it will easily keep for a year.
Steve