There are two ways to have one or more macros automatically executed at startup.
1. If you install Jim Walker's AtStartup extension in the KeyQuencer Extensions folder then the "AtStartup Macro" will be automatically executed as soon as the startup process is completed. The "AtStartup Macro" must be a text macro file created with the Macro Editor application and saved into the KeyQuencer Extensions folder. You may disable the startup macro by holding down the shift key before the desktop appears and releasing it when the Finder is up and running. This is by far the best way to execute a macro at startup, since no application has to be launched to execute the macro; and because no application is launched, there is no support for remote macros (i.e. macros to be executed on a remote target on the network). You may execute more than one text macro file by using "Open macro" commands inside the "AtStartup Macro" file.
2. If you save one or more text macro files (with any name you like) in the standard Startup Items folder inside the System folder, then the Macro Editor application is launched after startup. All the macro files are executed, then the Macro Editor automatically quits if the "Auto Quit" option is enabled. You may disable all the Startup Items by holding down the shift key while entering the Finder. This method is slower than using the AtStartup extension, since the Macro Editor has to be launched; you should only use it if you have to execute macros on remote targets when your Mac starts up, because network communication is only available inside the Macro Editor.