ctrl+t doesn't show percent complete

Yes it does

  aeg@bigwibble ~/ % cp bigfile /Volumes/data_sd1
  load: 1.60  cmd: cp 17686 uninterruptible 0.00u 0.09s
  bigfile -> /Volumes/data_sd1/bigfile   1%

Here's me hitting it 4 times:

    [/tmp]$ cp bigfile bigfile2
    load: 1.78  cmd: gcp 93420 running 0.00u 0.04s
    load: 1.78  cmd: gcp 93420 running 0.00u 0.10s
    load: 1.80  cmd: gcp 93420 uninterruptible 0.00u 0.16s
    load: 1.80  cmd: gcp 93420 uninterruptible 0.00u 0.26s
    [/tmp]$

What is gcp? It sounds like you have some alias setup for cp and that's interfering.

Try: /bin/cp bigfile bigfile2