According to my observation, after the end of the sale, it takes at least one or two months, sometimes it takes more time, if you choose by quality, I think it may be longer, but as a result listing on a good exchange.
Basically it's will be so easy if you are preparing a lot of money to pay the exchange site just like a few coins that paid a few millions dollars to get listed on the major exchange site. They are wanna get money and this what will do by exchange site to earn revenue from the product.