Check in with your music teacher about routine/ transition songs they are already using- if they have a welcome or transition song that works for you, use it!

Do not just play recordings of songs. Learn them and be able to sing them so you can really engage the kids.

If the song is too tough for you to sing, it is probably too tough for the kids. There is some not-great stuff floating around youtube.

If there are books that would lend themselves well to interactive sounds (one I used to do was "The Little Old Lady Who Was Not Afraid of Anything"), check in with with your music teacher about possibly borrowing materials or collaborating. I loved doing collaborative lessons with my librarian where she would read the book and then I would create a soundscape or other activity in music class.