Exodus 12:6
You must care for it until the fourteenth day of the month, when the whole assembly of the congregation of Israel will slaughter the animals at twilight.

Exodus 40:2
"On the first day of the first month you are to set up the tabernacle, the Tent of Meeting.

Exodus 40:17
So the tabernacle was set up on the first day of the first month of the second year.

Numbers 1:1
On the first day of the second month of the second year after the Israelites had come out of the land of Egypt, the LORD spoke to Moses in the Tent of Meeting in the Wilderness of Sinai. He told him,