I just posted on a similar thread in the 'Spirituality' forum, but here goes:
I believe in believer's baptism. The pattern in Scripture is that baptism occurs fairly soon after conversion (however, in my case, I was baptised at about 16. I did ask to be baptised younger, but the circumstances never really seemed right--either there weren't baptism classes going on at my church, or I was going through a shy phase, or my parents forgot about it... Not the best, but never mind).
In answer to the 'household of Stephanas' argument, it's perfectly reasonable to presuppose 'household' means 'excepting infants', if you can prove by other verses in Scripture that baptism is not applicable to infants. Just like I would, in some context, include my pets as part of my household; but if you said 'Are all the members of your household Christians?' I'd say yes, meaning me and DH. I wouldn't say 'Yes, except for the chickens', because of course the chickens aren't Christians.
So how does one prove that baptism is not meant for infants (and that therefore, they would be excluded as a matter of course from the term 'household', just as pets would be)? I think it's fairly clear from Scripture. Jesus commands believers to repent, believe and be baptised. As babies cannot, as far as we know, repent and believe, they should not be baptised. I realise some Christians see baptism as analogous to circumcision, and believe in infant baptism as part of a covenantal theology; but they are clearly not entirely analogous, as baptism is performed both on males and females. And while the Old Covenant contained both saved and unsaved members (Romans 9:6-8), the New Covenant is for believers only (Galatians 4:28).
ETA: Incidentally--and I'm not too clued up on the history of baptism, though I realise there is disagreement on exactly how early the practice is--the Didache, a very early teaching document about church matters, does not mention the baptism of infants, and in fact implies that adults/older children only are to be baptised. It speaks of having the baptisee fast for a few days prior to the baptism, and answer certain questions about salvation during the baptism process--both of which would be impossible for a baby to do.