I think in general surinams take longer to reach maturity. I've heard 4 years for females, though it really does depend on the individual snakes, though I think some people breed at 3 years if the female seems to be a good size. The female needs to have mature muscle mass and then a good reserve of fat, but BCCs shouldn't be powerfed to reach breeding size (well, any snake shouldn't be powerfed since it's not healthy, but anyway) because of their tendency to regurgitate meals that are too large or too frequent.
Usually no female (BCC or BCI except for dwarf localities) will be ready to breed at under 6 feet. Sometimes even those that are over 6 feet will still not be ready if they haven't gained muscle and fat reserves. It's like with people - sometimes an 11 year old girl CAN have a baby, but it's not healthy....
As for weight - I have no idea. I think that varies, along with length.
-----
Lauren Madar - OphidiaGems.com
1.0 Ball Python, 1.1 Hog Island Boas, 1.1 Hypo BCI, 1.1 Surinam BCC, 0.1 Green Tree Python