Mongoose connection/models: Need to always run on open?

I am using Mongoose 3 and the most obvious way to connect to database is

conn = mongoose.createConnection(...)
conn.on("open", ...)

Question is, do I need to define all my models in the open callback? If that is so, I will have to create a initMongoose.coffee that looks like

# initMongoose.coffee

mongoose = require "mongoose"
module.exports = mongoose.createConnection ...

# modelExample.coffee

conn = require "./initDatabase"
conn.on "open", -> 
    ... define model?
    modeule.exports = model # I think this does not work?

I think I read somewhere in Node docs that modules cannot be defined in a callback like that?

Since I am only using 1 connection, I think I can use

mongoose.connect ...

Which doesnt accepts any callbacks so I suppose is synchronous? Can I define all my models and thus queries right after connect()? It works at the moment, but it might be because its fast enough.