Well, I'm not an expert, but I'll give some advice (or at least my experience) anyway
I got my first snakes, 2 corns, in August of 2001 (daytona show). 4 months later, I got my bci. I don't think it was too soon. But you have to take into account I was 17 and my dad was whole-heartedly in support of getting the boa (technically she's half his).
Some things I've learned in the past 2 years:
1. GET A SNAKE HOOK. Last year, for some reason during feeding time I needed to reach into the cage and grab something (not the snake). I thought that I could just 'reach around' her and not get noticed, but no such luck. She bit and constricted around my hand, and I went 'AHHH!'. More out of surprise than anything else, though. She figured out soon enough that I wasn't a rat. Luckily she was only around 3' or so, but she did leave a little bruising on my hand. After that I promptly went and bought a 2' snake hook just in case I need to move her out of the way.
2. Don't let the snake wrap around your neck. Not out of fear of being constricted, but just the sheer muscle 'grip' that the snake needs to hold on will cut down on your blood flow. I tend to carry her slung over one shoulder, or over both shoulders and behind the neck. I don't let her make a full circle.
3. They are -very- strong. My snake is 6 1/2 feet of pure muscle. When she wants to go somewhere, it takes a little power to make her stop. Not like a corn where you can casually pull them back with no effort.
4. When she's hungry, she's hungry. My boa has a habit of sticking her head out of her hide when she's hungry. Another day, she'll have her head even further out. And so on, until she's cruising the cage like mad looking for a rat. She gets in 'feeding mode' very easily, before the rat is done thawing. (good sense of smell). Don't grab a boa when you're thawing a rat out in the other room.
5. They grow -fast-. For quite a few months she was growing an average of an inch a week.
6. An 'interesting' fact - boids in general seem to have poo with more 'form' than colubrids. Comparing poo of my corns, milk, and king to my BP, tree boa, rainbow boa, and BCI, the latter tend to have more shape.
My boa's poos right now are about the same size and shape as a standard human poo.
This makes it not as messy to clean up, but it sure scares the neighbors
Lastly, I've attached an image (however bad) of my boa, 2.5 years, 6.5', and my amel corn, same age, 3.5'. Not the best pic because the perspecive seems to make the boa look smaller than what she really is.