Residency Help

I’m applying to a Florida college and they ask for the “Name of the person claiming Florida residency and Date claimant began establishing legal Florida residence and domicile” and I’m not sure what they mean by “legal”. My mother moved to America when she was 13 legally, but did not become a U.S. citizen because she turned 18 before the 5 year wait period was over. Should I put the date she first moved here or when she became a U.S. citizen?

The date your mother moved here legally as an immigrant would be the date of residence & domicile.