I suggest you test in out of box BC to see if the send ahead qty and wait time are calculated correctly. for your case
operation 10 processed 21 qty to send ahead for operation 20 to start. the time spent is 0.95*21=19.95 so the starting time seems to be correct.
operation 20 processes 1.5 to send ahead to 40 to start. 1.5*0.95=1.425
6:49 am +1.425 min, so it make sense to start operation 30 at 6:51 am without taking the wait time into account
to start operation 40, operation 30 need to wait for 30 min from 6:51 am, which make the correct starting time of 40 7:21am
BC is indeed not calculating the wait time but I heard that BC doesn't calculate correctly if send ahead qty is used and it might explain why the wait time hasn't been accounted for in the scheduling.
Try to test another routing without the send ahead qty and see if BC calculate correctly.
