Damn! Once again with correct formatting. Gotta learn to use the Preview button.
I ran the following code on a 250,000 record address table with 21 fields

clear
use test excl
delete tag all
for lnI = 1 to fcount()
   fname = field(lnI)
   x = seconds()	
   index on (fname) tag (fname)
   ? fname + ":", seconds() - x
endfor
return

The first index to nearly 16 seconds to create. The following 20 index tags tok 1.5 seconds or less to create each. When I issued a REINDEX command on the table, all 21 indexes took less than 2 seconds each to create including the first one. Obviously, there is no accurate way to time this except to eyeball it with set talk on and set status bar off.