Unlike when walking, your hands and feet are locked in the same position while biking. You can wiggle your toes and fingers if you feel them getting cold, but this, at best, will simply delay the need to get to some place warm. If you have a long way to go, stop for some coffee, sit by the radiator. Your hands are hard to re-warm if they get cold, so if go for extra warm gloves and it should not be too much of a problem. See our Clothing pages for various recommendations.
Shoes are another matter.
Finding something warm enough that will still fit in the toe clips can be difficult. Check the Shoe page.