Census taking in Vermont began in 1791, and Vermont holds a unique position in census taking history for that fact. All other states existing at that time had their 1790 census conducted during 1790, however, Vermont didn't become a state until 1791, and Congress commissioned their census to take place that year. So, technically, the 1790 census in Vermont would be better known as the 1791 census.
Prior to 1791, Vermont's land was under direct confrontation between competing grants between two states, New Hampshire and New York. After the performance of the Green Mountain Men in the Revolutionary War, the federal government granted Vermont residents the right to become a state of their own, settling the border controversies.
Jay Mack Holbrook has attempted to build a record of people who were granted land in the state of Vermont, by looking at early New York, New Hampshire, Connecticut, and Vermont records. While he calls his book the Vermont 1771 Census, readers should not confuse that with being an actual Vermont census, rather then just a collection of names. In actuality, many of the names in the book, never actually resided in Vermont. They may have been granted land, but they either sold it, gave it to a relative, or just never claimed it.
The Vermont Genealogical Society has been working on a project to research all Vermont families in the 1791 census, by systematically sourcing the identity of all family members of those enumerated in 1791. Anyone purchasing or consulting these manuscripts will be light years ahead of those just relying on the 1790 census itself. Unfortunately, the first volume is already out of print; researchers can still get used copies from Amazon.
List of families enumerated in each volume:
You can still purchase volume 2 from the Vermont Genealogical Society, but they have no online method for payment.
If you wonder what you're going to get for your money, here's an example of an entry.
Best of luck with your Vermont Ancestors!