Lol love this. A 'special feeding program'? Sounds like a infomercial diet plan lol. A BCI is a BCI. There is no 'special program' unless your snake has been grossly neglected one way or the other. You feed them a mouse once every 10 days until they can take weaned or small rats. Then you feed them every 2-3 weeks until medium rats. Then you feed them every 3-6 weeks depending if its a male or you are planning to breed.
And if your 10 month old is almost 4', I am willing to bet it is overfed or it is older than you are guessing. If you talk to any other boa keepers on this page or even go look at what's for sale on FB or Faunaclassifed or Kingsnake, I bet you wont find a 10 month 4'. At 10 months old, it should be maybe 3'. So my guess is either you overfeed it or you're measurements are off as I have seen a lot of people say they have a 10' BCI and it magically shrinks to 7' when a tape measure comes close.
As for a BP, they always reject food lol. My girl goes months eating every week and then will quit eating for months. It's a BP. And I too have a baby female dumerils who is probably around 8 or 9 months old now and is maybe if I stretch her, pushing 3'. She was a fat little baby when I got her at like 2-3 months old and she gives my boas a run for eating if I give her a chance. She never rejects food even in shed too. And she is on medium mice once every 10 days too.
Bottom line it is your snake and in your care. People here are trying to help you but if you feel you are the 'expert' of boas, then more power to you but don't be surprised if your boa doesn't reach 20 years+.
Also I just noticed you said you fed your boa 8 meals in 4 months. So basically every 2 weeks. That's is pretty standard so now confused on what this 'special feeding program' is. So I guess some of the stuff I just posted doesn't apply. Sift through it for whats its worth lol.