John Gill Commentary Exodus 40:2

"On the first day of the first month shalt thou rear up the tabernacle of the tent of meeting." — Exodus 40:2 (ASV)

On the first day of the first month
Which was the month Nisan, as the Targum of Jonathan expresses it; which was the month the children of Israel came out of Egypt, out of which they had now been a whole year, excepting fourteen days:

shall you set up the tabernacle of the tent of the congregation ;
the tabernacle, which had a tent or covering over it, to which the people were gathered at times for religious service.