My kids coach helps in the JUCO to 4 year process but is often a conduit to conversations between player and 4 year coach(es). A couple of schools reached out to my son via twitter DM, others texts or calls, and then some thru HC. Son kept coach in the loop throughout his recruitment.
At sons visit to school he committed to he met a P that was at his second JUCO. He left JUCO #1 for JUCO #2 when the pitching coach (who recruited him) took a job with the Twins. I believe that he had to wait until the summer after Freshman year to change schools.
Related to this thread he said at his new JUCO he is not allowed to have any contact with 4 year schools on his own. EVERYTHING goes thru his HC/RC. Most likely pros/cons of both ways of doing it. Both he and my son both committed to new school.