How long can it take to add a token to the lists for trading on exchanges? This period the team should spend with an active advertising campaign for their platform
you need to wait for the announcement of the project about when the token sale will be closed. But I think that the audit period in IEO is not as long as in the case of ICO token sales
Projects get more benefits when launch IEO. And investors have more confidence in the quality of the token sale. The exchange contains information about the completion of the IEO in 40 days. And there is time for an advertising campaign.