Buy later on exchange is the best choice because now many ico are failed. Many ico don't enter the market. So instead of losing you better buy coins in the market.
In any case, the purchase of coins on the stock exchange is much more profitable, since the developers put the price of the company ico high enough, which is very far from reality. K with the current cryptocurrency market conditions No one from investors will be interested in buying coins on the company ico, Even with the use of a 50 percent bonus.