That is correct. The Part 1 Window for the second procurement event opens on March 30, 2018 and nothing is required before that time if a Bidder is considering participation in the second procurement event only.
However, we will note that if you do elect to submit materials in the first procurement event for a Project and the Project is qualified pursuant to the submission of the online Part 1 Form and all required documents, then if you wish to present the same Project in the second procurement event, you can do so simply by resubmitting the online Part 1 Form without changes during the Part 1 Window for the second procurement event.