Which Step Of Installation should i install Multi Db

i was following the step by step instuction to installing WPMU ...but somehow im not sure when do i install Multi DB Domain Mapping and Multi Domain...So i've installed multisite and enabled it..so is it too late...havent installed anything yet.Need A checklist of step by step(without instruction )

1.Create MySQL
2.Upload Wordpress (with wp-config.php changed accordingly and wordpress secret key)
3.Install Wordpress by going to the site
4.Enable Multisite[add define ('WP_ALLOW_MULTISITE', true); ]
5.Go Tool>Network and install Multisite
6.Create blogs.dir
7.Edit wp-config.php by removing line added in step 4 and replace with the one provided from Network Setup .Also change htacess as provided from Network Setup
8.Create mu-plugins
So far this is to get multisite working

So when should we start installing Multi-DB,DM and MD? and which ones first?

Feel free to add/edit the above so we have a great checklist guide and not forget or miss anything.