It is very fast, within a few minutes there will be a few zeds (usually screamers or dogs, sometimes cops) so its honestly very overwhelming. we do have sleeping bags in the room just after the entrance bridge (the room with the 3 "cots and some windows), and a temporary land claim block just outside of that room. I tried going into the poi editor but as I'm not familiar with it I don't know how to identify the zombie spawning stuff. they do seem to mostly spawn right on the outside of the walls (like 80% of the time) but that still lets them do damage on the base and when they are screamers its a forgone conclusion that we will have a bunch of dogs and cops loose.