I think Lenore suggested that without the bcp, you are not as likely to have a full supply at the end. I have heard of people doing it without the bcp. Some had success and achieved a full supply but it took 8+ months of pumping (she had an international adoption, so she had the time). I think if you have bf before, you are more likely to have success because your breasts might already be primed.
I would say I would just start pumping and see how it goes. I am betting it varies for everyone (as does the protocol - some never achieve a full supply, others do).
I personally did the protocol and had a full supply for my daughters within 2 weeks of pumping. I could not pump indefinitely, so prepping on the protocol and then pumping for less time pre match (or not at all as was the case in our stork drop situation) worked for me.
Good luck!
Jennifer