How can i date stamp a CSV file?

set feedback off
set pages 0
set lines 120
spool /gtxappl/Stock_Mirroring/Results/pyfs_allocablestock_supply240708.csv
select upper('item_id,shipnode_key,onhand')  
from dual;
select a.item_id || ',' || b.shipnode_key || ',' || b.quantity  
from yfs_inventory_item a, yfs_inventory_supply b 
where b.supply_type = 'ONHAND'   
and b.inventory_item_key = a.inventory_item_key;
spool off