Beginning in verse 3 begins a description of the offerings that were brought. The way that it was done was that each day one of the princes of Israel brought forth the offering from that particular family (that tribe). There were twelve of them. So that took twelve days for that to be done, and now where are we? On the twelfth day of the first month of the second year, the tabernacle was finally fully operational. We are now only two days from the second Passover they ever celebrated.