Jost became a linen weaver, and on 11 November 1704, married Anna Maria Merkel. She was the daughter of a prominent family of the Bonfeld-Wimpfen area. Two children of this marriage, Anna Maria and Maria Barbara, died shortly after birth. The third child, Mary, not listed in the Bonfeld church records, with a birthday of 1708 or 1709, may have been born after the family left for America.

Records of 1709 indicate that the families of Johannes Heydt and his son Jost (Hans Justus), emigrated. It appears that only four family members reached America: Jost, his wife Anna Maria, their baby daughter Mary and Jost's stepmother, Maria. Probably typhoid, severe at the time, accounted for the rest. Entire families were known to be wiped out.

Jost and Anna Maria lived in New York State three or four years, as indicated by the baptism of their next two children at Kingston; Elizabeth and Magdalena. The family then moved to Pennsylvania, near Germantown, now part of the city of Philadelphia, where they bought 150 acres on the Skippack River in 1714. Four years later, on 15 Nov 1718, they purchased 600 acres a few miles up the Perkiomen, for the price of 125 pounds. Here Jost built a grist mill just outside of present day Swenksville. Family tradition says he also bought slaves, which seems likely in view of the size of his property. It must also have been here, while near the Pastorious Colony at Germantown, a Quaker settlement, that Elizabeth met and married Paul Froman, a member of The Society of Friends.

The rest of Jost and Anna Maria's eleven children were: John, Jacob, Isaac, an infant, Abraham and Joseph.