diff --git a/src/timetable_gui.cpp b/src/timetable_gui.cpp
--- a/src/timetable_gui.cpp
+++ b/src/timetable_gui.cpp
@@ -525,7 +525,7 @@ struct TimetableWindow : Window {
 			}
 
 			case WID_VT_START_DATE: // Change the date that the timetable starts.
-				ShowSetDateWindow(this, v->index, _date, _cur_year, _cur_year + 15, ChangeTimetableStartCallback);
+				ShowSetDateWindow(this, v->index | (v->orders.list->IsCompleteTimetable() && _ctrl_pressed ? 1U << 20 : 0), _date, _cur_year, _cur_year + 15, ChangeTimetableStartCallback);
 				break;
 
 			case WID_VT_CHANGE_TIME: { // "Wait For" button.