I was in the same position as you, but my first track day in the M240i was just this past weekend.
My advice is do it. If it's an upgrade you are going to do in the future anyway, you might as well do it now so you get the most of your track time. Imagine how much it would suck if you paid just to end up having to take it easy on braking. I did RBF600, braided lines, EBC yellow pads and slotted rotors, but still feel like it barely sufficed.
Same advice on tires.
Make the most of your day by having the right equipment/being prepared
