The writer uses the word "For" to begin explaining why he is confused and asking God why he is not coming to help. (See: [[rc://en/ta/man/translate/figs-explicit]])
This means that he has been trusting in Yahweh since he was very young. Alternate translation: "even from the time that I drank milk from my mother's breasts" (See: [[rc://en/ta/man/translate/figs-idiom]])