well
first I timed how long it took for me to sprint from my door into my room, using the closest door. It took about 20 seconds. And that was really loud, it would take an assassin a bit long to do it silently
then I timed how long it took me to knock + pull back my bow. ~4.5 seconds.
That gives me an extra bit of time to put on my quiver so I can have another 15 shots on him.