You can't react quicker at this distance. Amazing how much faith people put in their reaction times.

If the truck hits the brakes to stop (say there's a queue of traffic ahead), you will have about 300ms to hit the brakes on your bike after you notice the truck brake lights come on.

Go do a reaction test online to see just how quick 300ms is.

You might manage to react in time for a minor brake check or lapse in concentration from the driver. But for an actual slow down, you're fucked.