Qq regularly talks about how to do it.

QQ software: First of all, you need to open QQ software-click Dynamic-Friends Dynamic-click the "+"sign in the upper right corner-click Call, and then click the clock icon on the right side of the screen, so you can choose the time to edit the copy.

QQ Space Software: After downloading QQ Space Software, log in with QQ account-click the "+"sign on the page-click Talk, and then click the clock icon on the right side of the screen to select the time for editing the copy.