Doesn't matter if you're 21 or 100. In the end, you're a rookie and high risk to insurance companies. They go more-so by experience/age ratio's (with other little factors aswell). You're car insurance and driving history makes jack all as it's not the same. I've had my license and insurance since 16 and thats 10 years now.. still barely makes any difference to my bike rates if at all.
When I was 20, on a 250R, I was paying 3200/year. Stayed that way for a while.. Getting a 600 as your first bike, insurance companies probably won't like you for a bit. But do keep shopping around!