At what time of year did Naomi and Ruth arrive in Bethlehem?

Answer: The start of the barley harvest

They arrived at the beginning of the barley harvest, which set the stage for Ruth gleaning in the fields.

“So Naomi returned from the land of Moab with her daughter-in-law Ruth the Moabitess. And they arrived in Bethlehem at the beginning of the barley harvest.”— Ruth 1:22 (BSB)