macOS Sierra: Open items automatically when you log in
You can have apps, documents, folders, or server connections open automatically whenever you log in to your Mac.
Add or remove automatic items
Choose Apple menu > System Preferences, then click Users & Groups.
Select your user account, then click Login Items at the top of the window.
Do one of the following:
Add a login item: Click the Add button below the list of items, select a document, folder, app, server, or other item, then click Add.
Remove a login item: Select the name of the item you want to prevent from opening automatically, then click the Remove button below the list.
Hide a login item: If you don’t want an item’s windows to be visible after login, select the Hide checkbox next to the item.
Note: Hide does not apply to servers, which always appear in the Finder after login.
Temporarily prevent items from opening automatically when you log in
If you see the login window, press the Shift key while you click the Log In button, then release the Shift key when you see the Dock.
If you don’t see the login window, restart your Mac, hold down the Shift key when you see the progress bar in the startup window, then release the Shift key after the desktop appears.