Where were the Israelites when Moses received the tabernacle instructions?
The Israelites were still in the wilderness of Sinai when Moses received the tabernacle instructions. Scripture indicates God gave Moses directions for building the tabernacle, and the people completed that work while they remained camped there, before the forty years of wilderness wandering ended and they entered the Promised Land.
Les explains that God gave Moses the instructions for building the tabernacle, and the Israelites accomplished all of it while they were yet down in the wilderness of Sinai. After the tabernacle was finished, the Shekinah glory came down upon it, and whenever the glory lifted and moved, they took down the tabernacle and followed it. This was part of the giving of the Law to the nation of Israel, which they carried with them after the forty years of wilderness into the Promised Land. The Law was given to Israel, not the Gentiles.