it doesn't matter when a user joined. what matters is if he is nice, if he contributes to threads in a constructive way, and generally don't act like he is a brain amputee.
all those things are not changed by the time you joined the community. it's just that older users often have something like a "nostalgia complex" and feel that they are better because back then when they joined all their friends that they consider cool guys joined. vice versa, newer users are often annoyed by the negative attitude older users have towards them.
tl;dr embrace new users, and respect old users, but no user is better than an other is simply because he joined earlier.