If your baby seems wired after you have coffee, it more than probably IS having that effect on him and for sure caffeine is no good for someone so small. But you could still drink it, just NOT before you are going to nurse. Use the same rule of thumb with ot that you would a glass of wine or a beer. If YOU feel it, don't nurse. You know the difference a cup of coffee makes for you right? When you are feeling that difference, don't nurse. Or as a previous poster stated, do it right AFTER you nurse.
Carolin is lucky. Her coffee drinking doesn't seem to have an effect on J. But lots of women DO notice a difference in their babies as a result of it. If you do than just rework the timing.