Welcome to our forum.
My first thought is I'm uncomfortable assuming non-monogamy without confirming it with the other person. However, maybe the music touring scene has a built-in culture of assumed non-monogamy.
The only other concern from my perspective is make sure you practice relatively safe sex, especially if you've just met the other person. The almighty condom comes into mind.
In most situations, I'd try to bring up being poly as soon as possible, first or second date. Simple is best: "I should let you know that I am polyamorous. Is that okay?" The person might not know what "polyamorous" means and if not, you can explain it to them.
I think it's always wise to be prepared to answer questions about polyamory, so study and learn. "Opening Up" by Tristan Taormino is a great book to get into, and on this site there's a Golden Nuggets board
to cover the basics.
Whatever you read and however you research, Polyamory.com is always a place where you can post your thoughts, questions, and concerns. Usually you get some pretty good feedback.
By the way, what made you realize you were into polyamory?
Glad to have you aboard.