O Apple Script pode fazer isso e você pode alterar facilmente o script e ativá-lo por meio do atalho do teclado Notificações:
tell application "System Events" to tell process "SystemUIServer"
click menu bar item "Notification Center" of menu bar 2
end tell
tell application "System Events" to tell process "NotificationCenter"
click radio button "Notifications" of radio group 1 of window "NotificationTableWindow"
end tell
Hoje:
tell application "System Events" to tell process "SystemUIServer"
click menu bar item "Notification Center" of menu bar 2
end tell
tell application "System Events" to tell process "NotificationCenter"
click radio button "Today" of radio group 1 of window "NotificationTableWindow"
end tell