Creating the SGI faster

thanks but a simple / Covered or Partition Index creation taking 4-6 hrs to complete on this much of data volume . we have TB’s of data and I am simply asking any method to or guidelines to increase Index threads during creation to make it faster . It s a hrs and hrs of wait just to see what is right indexing approach . Trying to see if this could be avoided . We have Index in GSI and not memory optimized . We are not concern on h/w resources now but need to know FASTER approach to create Index.
thanks