Help is on the way. Check your email. One of the biggest challenges of this piece is the counting. I have marked in lots of cues and split the multi-rests. The cadenza is rhythmic, and often is conducted. The harpist has to be together with the violinist, so it really helps to have a copy of the violin part and know exactly what to listen for. Ask to be as close as possible to the soloist, so that you can hear each other. Good luck!
I was just about to suggest that David contact you when you graciously responded! Would you be so kind as to send it to me (Rosalind Beck), also? You should ask David for the part he created for the Leroy Anderson “Sleigh Ride” in return.
It is a tough piece to learn so quickly. I have had to play it several times without much notice as it was a concerto competition winner and wasn’t on the schedule. The cadenza was always conducted when I have played it. Last time there was an accelerando at the end of the cadenza. 12 goes by so quickly it really has to be memorized. Probably memorize 21 too because of constant tempo changes.