for some reason there are a lot more posts about hair growing back every time after using IPL machines, especially on darker skin types like yours. that’s why I’m not a fan. you might get better results with diode like LightSheer or a Yag if you have dark pretty coarse hair. The only good results I’ve heard people get from IPLs is when they have type I-II skin and very dark coarse hair, usually on bikini. It’s not very encouraging.
Yes, get maybe 3-4 spots done on your leg at various fluences going up by 5 joules or so every time and then see what the highest one you can handle. if you don’t get any negative reaction from the highest setting out of those, i would go with that setting for your entire treatment later.