That sounds a bit hot for my money.
My (almost) standard these days is to set it to 230°C and 20 minutes.
This usually gets me to 1st crack about 12 minutes in, when I reduce the set temperature to 220° over a minute or so.
2nd crack usually starts about 18 minutes in and I am pulling most beans either just before or just after that time for a roast level of CS 9 to CS 10.
All this of course can vary with the bean.
Very chaffy beans usually mean a roast quantity of 250 gm rather than 300, and Monsoon Malabar is measured by volume not weight.
BTW the Emergency Stop is just that, and can be hard on the equipment.
I know its a bit slow but I just cool in the machine.