Both by sons started the process of teething early but DS1 got his first teeth at about 7.5 months and DS2 hasn't gotten any. *Usually* the first two teeth they get are the bottom middle, and those are covered by their tongue when nursing so it's not an issue. With DS1 I never really had an issue with him trying to bite after the top teeth came in, but the few times he did I would just take him off for a couple minutes and put him back on.
Re: Teething while nursing