Judging by evidence in the text, it takes between six and seven months for the older brother, who is never named, to teach Doodle how to walk. The brother reports that they began the task in the spring when Doodle was five years old. Since spring starts in late March, the reader might assume that it is either March or April. After months of painful work, Doodle eventually is able to stand on his own and take a few steps by his sixth birthday on October eighth. The experience reveals the level of dedication the older brother will display to make sure he is not embarrassed by having a crippled brother. He admits that he taught Doodle to walk because of his own pride:
They did not know that I did it for myself; that pride, whose slave I was, spoke to me louder than all their voices, and that Doodle walked only because I was ashamed of having a crippled brother.
In Doodle, it reveals an individual with a great deal of perseverance. But, more than that, it shows a boy who deeply loves his older brother and will do almost anything to demonstrate that affection. At the end of the story, we realize that Doodle is disappointed that he is not able to live up to his brother's expectations and, unfortunately, dies thinking that he has let his brother down.
It probably takes about 9 months to a year to teach Doodle to walk. According to the text of the story, when Doodle is five, Brother begins to feel embarrassed that Doodle can't walk. He then takes him to the Old Woman Swamp and teaches him to walk. On Doodle's sixth birthday, they show the rest of the family that Doodle can walk. Thus, sometime between becoming embarrassed about having a 5-year-old brother who can't walk and Doodle's sixth birthday, Doodle learns to walk.