Do anyone in here have experience in doing/creating a demo.

I´ve been assigned to do a demo, in the other part of our country (dk)
I´ve only done one small christmasdemo before for about 40 local florist, but I was with my old boss, and hide most of the time behind a big picture with clued leaves. and only came forward when I should should show something. and mostly let the talking up the boss.
The only advise I got afterwards from a guest was: Don´t hide´yourself on stage. nothing about the things, ideas or tecnichs I broght.

and I talk about plant for outdors once at the elderhome. The don´t know the difference anyway and most of them could´nt hear anything.

But this Spring demo is huge. And I´m rather nerveus.
I can´t hide this time. Don´t know how I let myself talk into it.
Well I do know. I liked the money they offered.

But I´m affraid I don´t have enough good stuff with me. Affraid they won´t like it. But they did hire me. Something I´ve done most be right.
But what if I blow it. and disapoint them.
But anyway I´m going out of my mind with questions.
And whatever selfesteam I thougth I had. Is about gone now.
I feel so green.

Is this normal.?

please someone, help