During Challenge creation, you can set when a challenge will start. Use the calendar tool to set the start date, then in the Duration field, set how many Days, Weeks, or Months the challenge will go on for. Once you enter a number in the Duration field, you will be able to see the date that the challenge is set to end. Once a Challenge is published, you can not edit the start date or the type of Challenge; however, you will be able to edit the duration/end date.
Publish Date: During Challenge creation, you will choose when you want to publish this activity. You can choose to publish the Challenge immediately or schedule it to publish for a date in the future. You can schedule a challenge to be published before the start date if you wish. This allows your employees to learn about the upcoming engagement opportunity, but they won't be able to participate until the actual start date of the Challenge.
If running a basic Challenge, use Repeat challenge to-dos on each duration to recycle the same todo, or set of todos each duration (Day, Week, or Month). You will not be able to enable repeating to-do's, once a Challenge is published.
If you need to edit or remove a scheduled publish date to publish the Challenge immediately, you will need to clear out the current scheduled date, before change the toggle from "Schedule Publish Date" to "Publish Now".