Awesome
Have fun with it, stay safe out there.
Learning to ride the track really well, and your racing tactics, technique on the bike and your fitness gains are going to matter the most for improving your times - over at least your first year or so, probably.
Race as much as you can. All types. Go to training sessions with experienced trackies. Get really good at riding the track.
Actual training will matter a lot more than supplements too. Honestly, I wouldn't bother with much but for reference, I use caffeine (coffeeee...
, plain whey protein isolate on most gym days, and a standard creatine monohydrate in season (when I can be bothered, which is rarely). Nothing fancy. You're talking pretty marginal gains from these. Do check the WADA list if you're getting into supplements - and some of the pre-workout things have some dodgy uppers in them! I'd avoid personally, for jittery reasons as much as anything.
Like I said, technique will trump any strength gains. You're already strong. But you'll need to learn to put your power down on the bike, and in different situations on the banking, and find out what works for you re. gears, tactics, etc. Hopefully your BMX experience will make this a quicker learning curve... I recall Wade Bootes tried out track sprinting for AUS with some level of success when I was younger, but I think he went back to MTB eventually.
*Find a good local sprint coach if you decide to get serious about sprinting, and train with the local sprinters*. But try everything. Just for fun. For sprint-specific training,
you will get the biggest gains from training on the track with sprinters who know what they're doing, and especially from following them when they do their flying 200s - this will help you learn the 200 line to follow, and to get used to putting the power down on the banking. Technique matters a lot. Line matters a lot. No matter how powerful you get, you can lose a lot of time from starting your sprint too late/at the wrong time, taking the wrong line and not getting the full benefit of the banking.... read that UpUpUp site regarding F200s once you get into it a bit more.
So yeah, F200 time depends
a lot on how good your technique is, as well as sustained power output, so I don't want to say anything potentially discouraging. You'll improve quickly if you practice. Assuming you're on a decently-fast track, anything around 14-13 seconds is actually quite good for your first few F200s, even if you have a lot of power, due to technique/line variations. Sub-12 seconds is getting competitive at a local level generally, mid-to-low 11's is usually competitive at national level in Masters 2. At the UCI world-champs level, the best Masters 2 guys in their 40's are still quite fast and can do sub-11 seconds. Like 10.6-10.9. But then you have to do match sprints anyway, so you have to nail the tactics down too
PS - buy a skinsuit. They're faster and look more professional. Looking professional is key. And did I mention to buy some track straps for your pedals, and crank the tension up? Unclipping on the banking sucks.