I think only 500 miles is a little too soon... but generally the earlier the better.
With that said (and I think this goes w/o saying but I'll say it anyway) you should be 100% comfortable w/ all normal operations of the bike. Shifting, braking & steering etc should all be second nature.
I did my first track day 3 short months after I got my first bike and I had only put about 5k miles on it by the time I brought it to the track. By the end of the day I had learned a SHITLOAD and made a ton of improvment. And as a bonus, my left knee my puck was skuffed & my bike was still intact
