Both my sons were Aux before going active duty. One really didn't have much chance to do anything prior to leaving. The other joined in college, and once he finished was augmenting an active duty station. He qualified as a watchstander and started on boatcrew while he was in the enlistment process. His recruiter told him to keep it up as that made him more valuable at his first station. Both have maintained Aux membership.
There is another high school kid in our Aux division who has qualified as a watchstander and put in a lot of hours, and who is in the process of applying to the Coast Guard Academy. I know that will look good on his application.