PlannerDatePicker1.Calendar.YearStartAt.ISOWeekNumber:= true;

procedure TForm2.PlannerCalendar1CellDraw(Sender: TObject; Canvas: TCanvas;
  Day: TDate; Selected, Marked, InMonth: Boolean; Rect: TRect);
var
  da,mo,ye: word;
  s: string;
begin
  DecodeDate(day, ye, mo, da);
  if day = int(Now) then
  begin
    Canvas.Brush.Color := clYellow;
    Canvas.Rectangle(Rect);
    Canvas.Font.Color := clBlue;
  end;
  s := inttostr(da);

  if odd(Da) then
    Canvas.Font.Style := [fsBold];
  inflateRect(rect,-1,-1);
  DrawText(Canvas.Handle, pchar(s), length(s), rect, DT_CENTER or DT_VCENTER);
end;

with plannercalendar1.Events.Add do
begin
  date := EncodeDate(2005,2,14);
  hint := 'Valentine';
  shape := evsCircle;
  color := clRed;
end;

plannercalendar1.MultiSelect := true;
plannercalendar1.Dates.Add.Date := EncodeDate(2005,2,20);
plannercalendar1.Dates.Add.Date := EncodeDate(2005,2,22);

var
  StartDate: TDateTime;
  i: integer;
begin
  StartDate := EncodeDate(2005,2,20);
  plannercalendargroup1.MultiSelect := true;
  with plannercalendargroup1.Dates do
  begin
    for i := 1 to 7 do
    begin
      Add.Date := StartDate + i - 1;
    end;
  end;
  plannercalendargroup1.UpdateDates;
end;