Although you can update initiative at any time, the information in Initiative Data such as percentage complete, is used to track progress. You must be the owner or creator of an initiative to update it.
To update initiatives:
From the Browser View or any report, click the object to which the initiative is assigned. Click Initiatives and then select the initiative to update.
From the Browser View, select Reports, then Initiative Status. Right-click the initiative and select Edit.
Change the appropriate settings. See Creating Initiatives.