Ellysia, dont be too upset over the false labour. Wrt the > 4cm/6cm, I seem to remember it is too late if more than 4 cm. But I checked it out and it seems that it is not whether how dilated but how fast the medical staff can get to the mother and administer the epidural. There is an article appended below that might be useful:
"When is it too late to get an epidural?
There are a few instances where the medical staff may simply not be able to get pain medication to the mother in time before the baby comes. One example of this could be if the mother's labor progresses quickly after she has been at the hospital for some time and/or the anesthesiologist is occupied with another patient. Another situation might be if the mother's labor is fast from the start and she is close to pushing when she arrives.
If the mother's cervix is 8 cm or more when she arrives at the hospital and labor is progressing quickly, there simply may not be adequate time for the medical staff to admit her, draw blood, monitor the baby and get enough IV fluid in before she starts to push. On the other hand, if the mother has been admitted to the hospital and all of the pre-anesthesia work is finished and the anesthesiologist is available, she may in fact be able to get an epidural even late in labor. It actually has more to do with how quickly the staff can attend to the mother, rather than a certain number of centimeters dilated that prevents her from getting pain medication."