Yep. I usually go by activity levels with mine, since it's really hard to keep track of when each litter was born around here. Once their eyes are open and they are bouncing around, they are large enough to be fed to a young BP. When they are seen drinking from the water bottle and nibbling the food, they are weaned and considered "small" adults - the next size step up. After that, it's best to compare their size to the diameter of your snake.