Trackday Start It Slowy
You shouldn't even be thinking about your speed for the first few events. It should be all about enjoyment, the thrill of riding close to your friends, and experiencing the real capabilities of your shiny new motorcycle and of yourself.
Consider your first venue carefully. Perhaps you live 10 kilometer from a race track, but taking your new motorcycle to the fastest track in the country for your debut could be scary with other motorcycles flashing by 100km/h faster. Equally, piloting a Kawasaki ZX-10R round a tiny track officially created for karts is also a silly mistake.
Over time you'll start to learn how to control your motorcycle correctly, thinking more about things like choosing lines, identifying braking markers, and adjusting your technique to find more speed, but remember you are not a professional racer. If you get overtaken it doesn't matter, you'll still get paid at the end of the month. Even in a year's time when you're a total addict, you've been to tracks all over the world, and have bought yourself a hot WSB capable 1,000cc machine complete with pit crew and transporter, there will always be someone quicker. The sad reality is it'll probably be some fat, scruffy bloke riding a knackered old motorcycle. It won't matter though, you'll still go home with an indelible grin.