Load NVM on demand

.bashrc

export NVM_DIR="$HOME/.nvm"
# Default node version
alias node="$HOME/.nvm/versions/node/v8.11.1/bin/node" 
# Function to load the original nvm and execute it
load_and_exec_nvm(){
    unalias node
    unalias nvm
    echo "Loading NVM..."
    [ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh"  # This loads nvm
    [ -s "$NVM_DIR/bash_completion" ] && \. "$NVM_DIR/bash_completion"  # This loads nvm bash_completion
    echo "Executing NVM..."
    nvm $@
}
# Default nvm, the wrapper to load it and execute it
alias nvm="load_and_exec_nvm"

This snippet let you load NVM just when you need it, in order to save time and resources.
It also set a default node version, just in case.