While in EN57/71 EMU you have electro-pneumatic brake, wich activates brakes in all of carriges at the same time, in trains pulled by locomotives things are different. You have to account time while performing braking, when air makes it's way into every carrige. This also works in the other way. Use brake confidantly, as you do normally, but release preasure when youre not quite there yet on a speed. For example, if you want to end up on 80kmh, start releasing at 90-95. Of course this differs on the weight of the train. Longer train takes longer to release.