Secondly, they aren't white.. While some double merle dogs are almost pure white, they can go the complete range all the way up to a dog that you would think is a just a normal merle (most fall somewhere in the middle).
In between five and six months, your baby usually starts to sit up with your help, holding his head in an upright position, keeping the back straight. He may even be able to sit for a second or so without taking any assistance from you, before toppling down after a while [1] .
Whereas if they really like to be on their tummy, they might roll over closer to that 4-month mark. Sitting up can occur anywhere from 6 to 9 months of age and crawling, from 9 months to 1 year. Not all kids actually do a normal standard crawl. Sometimes kids do an army crawl, other kids do a one-leg and push with the other. It's just a mode of transportation.