hey david,
sorry for the delay, been on holiday.
i use an expression on a layers opacity property which is controled by the position of a composition marker in a different composition.
the expression is:
if (time < comp(“ControlComp”).marker.key(“0”).time)+1/25) { 100 } else { 0 }
the value “1/25” equals one frame in a 25fps composition. if you have a different framerate, you should adjust this value.
if you have any more questions, don’t hesitate to ask.