You an get into guilds at any time, and in general the World of Warcraft community is very helpful and appreciative. Unlike people in some games, they atually remember what it's like to be new, and how nice it was for people to help them out, instead of just goign "dude u nub, get lost!!!!11111!!11!!one!11eins!!!"
A lot of guilds are actively recruiting, but most of those guilds are awful. Just ask around, if you can join peoples' guilds.
And so he said, "and there will be delicious cake", and with those words, I said, "I see what you did there..."