Junior is used after these nouns:
college, high school, office

be

very
a very junior officer

fairly (BrE), relatively
a relatively junior member of staff

to
John is still junior to me at work.

Junior is used with these nouns:
athletics, barrister, champion, championship, chess, clerk, colleague, college, counsel, division, doctor, employee, executive, faculty, fellow, football, grade, high school, hockey, league, lecturer, management, manager, member, minister, nurse, officer, official, partner, position, professor, rank, reporter, rugby, school, season, senator, single, soccer, staff, team, tennis, year