This article is from the Care of Orphaned Kittens FAQ, posted to rec.pets.cats newsgroup. Maintained by Sharon Talbert with numerous contributions by others.
A kitten's eyes are generally fully open by ten days old (they begin to open at seven days). By three or four weeks a kitten is mobile and able to eat at least some solid food. The kitten is also ready for the litterpan as soon as it can toddle to it. (I recommend introduction to the litterpan by three weeks with expectation of seeing some independent use of the pan by four weeks.)