What does the 1900 U.S. Federal Census provide for the month and year of birth for Ole? What does it say about his immigration year? If he lived long enough to be in the 1910-1920-1930 censuses, what was his year of immigration in those?
Were any of the children born in Sweden or Denmark? If so, provide the same details on those children too.
I am not researching these people but most who try to help are not related. More needs to be provided to make a search in databases, etc. worthwhile.
By the way, Olaf is the NORWEGIAN spelling of Olof/Oluv.