I wanted to wait until 6 weeks, but had to take him out with me alone and gave in at 3 weeks. Now we mostly use one if I'm out alone, or we're at church in the middle of service.
However, we've gotten to where we will offer it at home. He's not very partial to a pacifier in general (we use mam & some fisher price ones, I've offered both from the beginning as I'm hoping he doesn't get attached to only one kind and create issues if we lose them or something), and usually just spits it out. However I try to always offer the boob first if possible, and I can usually tell if he just wants to comfort suck as he won't stay latched on, but will keep taking it, suck a few seconds, pop off, fuss, latch on again, etc. He would happily suck on my (clean) pinky finger, and in the end I decided that really wasn't any different than a paci. Both are a nipple substitute.
I haven't noticed it affecting BF or his latch or anything. Like I said, sometimes he takes it, sometimes he doesn't. If he won't take it and is still fussing, then I offer the boob again.
If he falls asleep with it, I remove it from his mouth as I don't want him getting used to waking up and having it. Overall DH and I both hate pacifiers, especially seeing toddlers with them, but we happen to have a high-sucking-needs baby, so what can we do?
My mom used pacifiers with all of us but said we were off of them by 6 months, so 6 months is what I'm shooting for too. I've read that often the need to suck as much diminishes when they start solids (or at 6 months maybe? I can't remember which, but I plan to start solids at 6 months so it's the same to me) so hopefully I can do that