Vundle load plugins while still in .vimrc

Question

I'm trying to create my first own .vimrc file. I'm having some trouble when trying to load plugins with Vundle. For example, I want to use vim-airline, so I have (in the correct place I believe) in my .vimrc file this:

Plugin 'vim-airline/vim-airline'
Plugin 'vim-airline/vim-airline-themes'

I installed them using :PluginInstall succesfully. However, when I try to set the theme for the airline plugin, using in my .vimrc:

AirlineTheme luna

It doesn't work; vim says on startup E492: Not an editor command: AirlineTheme luna. When I continue and manually do :AirlineTheme luna while vim is running, it works. So for some reason, I can't use any commands provided by the plugins in the .vimrc file. What do I do wrong, or how do I circumvent this issue?

For reference, here is a stripped version of my .vimrc:

" ====== Load Plugins ======
set nocompatible              " be iMproved, required

filetype off                  " required
" Set the runtime path to include Vundle and initialize
set rtp+=~/.vim/bundle/Vundle.vim
call vundle#begin()
" Vundle manages itself
Plugin 'VundleVim/Vundle.vim'
" Add other plugins to Vundle
Plugin 'vim-airline/vim-airline'
Plugin 'vim-airline/vim-airline-themes'

call vundle#end()
filetype plugin indent on


" ======= Allow for project specific .vimrc files =======
set exrc
set secure


" ====== Configure Plugins  ======

" Airline Theme
set laststatus=2
AirlineTheme luna

Note that it is the very last line that does not work.

Answer 1

That command from the plugin is not available, until sourcing the vimrc is actually done. So either explicitly set the theme using let g:airline_theme = 'luna' which is the documented way to set your airline theme, or wrap your command into an VimEnter autocommand.

Answer 2

Turns out I was able to fix it using this:

let g:airline_theme = 'luna'

For now, I'll assume that the commands created by plugins are not available in your .vimrc file itself.

Answer 3

If you are editing your .vimrc file and want to load/ attempt to load it you can just run :so %

Here is a link to another answer that explains this further.