I do like the dual movement of the ore train departing and the other shunting, often something forgotten particularly if operating alone. One of the highlights in my Alexisbad station is the triple departure, one in the Down direction the other two Up, one the Gernrode the other to the Harzegerode branch leaving the station to it’s slumbers for a while.
Ok back to your departure, assuming the signalman had clearance with the line clear to the next Station, once this had been obtained the signal could be pulled off allowing the train to depart once the brake van has been attached and the guard given the ‘right away’. But as always superb to see your operations, my comments only given to help in that regard.
Is you line assumed to have “block bell and token” working or “staff and ticket” as the real SLR was? If the former there would be token release equipment in each station at a signal box, the later much simpler with just a bell and a responsible person at each station to authorise movement.
It can get complex with staff and ticket, though many trains can pass before the staff nothing can go the other way without the staff which could be a few tickets away. I had to re-plan my Timetable somewhat when I implemented staff and ticket working, a system not so far as I am aware prototypical for a German Railway but found essential to stop ‘cornfield meets’ with multiple inexperienced operators. A couple of workings were added just to return the staff as it only proved practical to have 1 ticket train and 1 staff train then a train or two the other way. Tricky when the 3 trains on the line start from the same station.