Re: Sand boa help!
A lot of shedding depends on the individual. Usually, it takes my snakes anywhere from 6 days to two full weeks to shed. I can usually tell with sand boas when they're ready to shed because their eyes will start to dimple, at which point I put them in a container with a wet rag and a little bit of excess water and they get the job done in an hour or so. Or if I catch them shedding and they're having problems I'll do that as well. My sand boas aren't the best at shedding, and while I've never had huge problems with retained sheds, it will often be in patches. I've only had a handful of full sheds from these guys, and that's being liberal with my definition. So don't be alarmed if you see it's shedding in patches.
Another point I'd like to make is that sand isn't great for them. I've had them on it once and it was a pain. Expensive, difficult to clean, and it'd get stuck in their teeth to where they couldn't remove it. I keep them on dry eco earth now and if they're shedding I can spray the bedding down a little.
I do not recommend anything heavy though, as they will try to crawl under anything you put in. It could be a rock on the bottom of the cage and they'll find a way under it. This could be dangerous for them. I have cork slabs in all of my cages which they use as a hide and to rub against during a shed. That's what I would recommend, definitely not a rock (although I suppose one would be fine granted it's not too heavy).
Don't over think the shedding process though. I don't handle them, but I do unearth them once every few days or so to see how they're coming along. Enjoy her, sand boas are a great species to have!