We got married about a year after being engaged, but from what I know about other couples, that's fairly quick. I know a couple who have been engaged for two years and still have no concrete wedding plans whatsoever. For some people getting engaged is just a committment thing, it doesn't mean you have to start planning your wedding and everything right away or even know exactly when you want the wedding to be. It's not weird, whatever feels right for you :)
I'd allow at least nine months for all the wedding planning though, it can get pretty hectic if you try to squash it all into a short space of time.
Congratulations also
~Michelle