In our district, everyone who scores at or above 95th percentile on standardized grade-level testing gets invited to do the Duke TIP's 7th grade talent search, and most who qualify do - almost all of those kids end up taking either the SAT or the ACT very close to their 13th birthdays (either before or just after), and it is not based on having particularly wealthy or involved parents. I'm sure lots of schools in the JHU catchment area do the same. I wouldn't say that practice alone would get you to the point where you could qualify for the SET.