Your desktop. Written down.
You can use NixOS for the ordinary things: a browser, documents, calls, music and work. You choose the desktop environment. NixOS supplies a way to manage the system underneath it.
Pick the desktop you like.
GNOME, KDE Plasma and other desktop choices do not require you to build your own interface. The graphical installer offers desktop options; a minimal installation is there for people who prefer to assemble more themselves.
A tiling compositor can come later. So can the complicated configuration repository.
Upstream references (1)
Check the applications you actually need.
Look up your essentials in Nixpkgs before installing. Flatpak is another option for desktop applications. A downloaded Linux binary or AppImage may need additional support rather than working with a double-click.
Write down the tools you cannot do without, including anything required for work, and test those first.
Upstream references (3)
Test the boring hardware details.
Boot the live image. Check Wi-Fi, sound, your camera and external display. Try suspend and resume. A working installer screen is not the same as a laptop that works well through a normal day.
Let your configuration grow at your pace.
Start with the system configuration. Home Manager can later manage selected user applications and dotfiles. You do not have to move every setting at once.