The main thing is don't do it abruptly and while other changes are happening in your child's life. If you're moving him to a new group, relocating, or something stressful happens at the same time, weaning off the pacifier will only increase his anxiety. Also, don't scold him for using the pacifier or make him feel ashamed - it'll make the object even more meaningful and desirable.
At around 18 months you can start, and there is real risk to his bite and speech, but it's not critical at this age. Here's what works best: limit the pacifier to specific situations (for example, only before bedtime), and during the day offer an alternative - a soft toy he can cuddle, or even just more physical contact with you. At the same time, gradually reduce the amount of time your son keeps the pacifier in his mouth. Don't "lose" it or make up stories about the pacifier breaking - kids catch on to that pretty quickly.
Do this gradually over a couple of months, and by age two the process will go almost unnoticed. If by three years nothing has changed, then it makes sense to be more firm about it, but there's no need to rush right now.