At t0, you say zero. At t1, you say one. ... At t7, you say seven. Positive seven is what you say while your clock says t7. Negative seven is what you plan

At t0, you say zero. At t1, you say one. ... At t7, you say seven. Positive seven is what you say while your clock says t7. Negative seven is what you plan and "will" say at t7 while your clock still says t0.