In the second year after leaving Egypt, in which month was the tabernacle set up?

Answer: The first month

The tabernacle was set up on the first day of the first month of the second year, as the Lord had commanded.

““On the first day of the first month you are to set up the tabernacle, the Tent of Meeting. So the tabernacle was set up on the first day of the first month of the second year.”— Exodus 40:2, 40:17 (BSB)