todo-always-add-time-string

todo-always-add-time-string is a variable defined in `todo-mode.el'.
Its value is

nil

Documentation:
Non-nil adds current time to a new item's date header by default.
When the todo insertion commands have a non-nil "maybe-notime"
argument, this reverses the effect of
`todo-always-add-time-string': if t, these commands omit the
current time, if nil, they include it.

You can customize this variable.