TON is listed on few exchange but make sure when you pick the exchange check out their 24 hour trading volume to make sure there is enough volume for you to trade. You can use MEXC as i have used it before to trade ton and their transaction is pretty fast. If possible you can use TON ecosystem AMM project that work like uniswap. I have used one called stoneFI i think. They also have enough volume and token listed in their dex so there should not be any problem for any big order.