My daughter took the SCAT in 2nd grade, she scored a 445/92% Verbal and 447/90% Quant (Math). We did go over the format of the test, and very briefly the idea of analogies, as she hadn't really done that before. I printed out the practice questions for her to get a feel for the structure of the test. All told, she probably spent 30-45 minutes in "test-prep." The tests are normed for 2 grades above, so that is normal for the SCAT.
As a point of reference at the end of 3rd grade she took the ITBS for end of year 4th grade, because of a considered grade skip (above level testing), her score here were:
Reading: 95%
Math: 99%
Social Studies: 98%
Science 99%
Composite: 99%
No preparation for this, as she had taken the ITBS before.
We homeschool now and do use Hopkins online coursework, as well as Northwestern University's gifted online coursework. It is a God send