Newbie to the track, Tire Help?

Hey guys a member of the forum for over a year and half now and Ive just joined my first car club. Been doing a lot of replacing on my 2005 e46 and I'm also a college student. I can't wait to get it on the track and learn from people who have experience driving on track but Im not sure to do about tires. This summer i just put a new set of Toyo Proxes 4 on. obviously not a track tire but still pretty good for a road tire. Can I use these in the mean time until i can afford 300 dollar slicks or will they eaten up/have no grip? I assume used slicks aren't really a thing but if they are can someone point me in the right direction? Finally should i stick with the pressure that BMW calls for on the road or drop them down a little. Obviously ill have to play around depending on temperatures and tires and what not but I'm talking as a general starting place.

Thanks

Newbie to the track, Tire Help?