I'm curious about how long I will be able to return my investment?
It's difficult to answer your question, but I think it depends a lot on the project's development, if the project follows the roadmap as announced in the initial ANN so the expectation of return must be quick.
As a rule, going to a cryptoexchange gives a price higher than the one at pre ISO sale. After that, the price is already dependent on the development of the project, it may decrease.