Emacs/docs/latest/emacs/Early-Init-File

49.4.6 The Early Init File

Most customizations for Emacs should be put in the normal init file. See Init File. However, it is sometimes desirable to have customizations that take effect during Emacs startup earlier than the normal init file is processed. Such customizations can be put in the early init file, ~/.config/emacs/early-init.el or ~/.emacs.d/early-init.el. This file is loaded before the package system and GUI is initialized, so in it you can customize variables that affect frame appearance as well as the package initialization process, such as package-enable-at-startup, package-load-list, and package-user-dir. Note that variables like package-archives which only affect the installation of new packages, and not the process of making already-installed packages available, may be customized in the regular init file. See Package Installation.

We do not recommend that you move into early-init.el customizations that can be left in the normal init files. That is because the early init file is read before the GUI is initialized, so customizations related to GUI features will not work reliably in early-init.el. By contrast, the normal init files are read after the GUI is initialized. If you must have customizations in the early init file that rely on GUI features, make them run off hooks provided by the Emacs startup, such as window-setup-hook or tty-setup-hook. See Hooks.

For more information on the early init file, see Init File in The Emacs Lisp Reference Manual.