Dating in 1910
The collar may be wide like the 1890's or sleeves off the shoulder like in the 1840s and 50s, the scalloped hems in 1870s.
All infants boys and girls wore long dresses like these until they could walk.
The There was a book by Frances Hodgson Burnett in 1885 that mentioned this suit that became a fad.
Knickers (knickerbockers) were worn by young boys, The knee pants were full, closed at the knee with buckles, buttons or simply cut off at the knee.
1840 to 1850 would be a daguerreotype or ambrotype.