Old Style Dates - Prior to 1752, the British Empire (and before 1 May 1707, the English Empire) used a dual dating system. Colonial Virginia was part of the English and British Empires and used the same dating system. The traditional year began on January 1st, but the new legal year began on March 25th. Dates between Jan 1 and Mar 24 would usually be written with both years.
For example, Richard Womack received a Virginia land patent on 15 Mar 1672/1673, with 1672 being the legal year, and 1673 the traditional year. The traditional year is what we use now, and should be used to calculate time between dates. For example, the 300th anniversary of Richard Womack's patent was 15 Mar 1973. It was NOT 15 Mar 1972. In records prior to 1752 with dates between Jan 1 and Mar 24 and just one year listed, we should assume the legal year was meant, and add one to get the traditional year.
Court records used the legal year, which is why we see court proceedings for Jan 1708 following Dec 1708. In our current reckoning, Jan 1708 (legal year) is considered Jan 1709.
The dual dating system was confusing, and was abolished throughout the British Empire by the Calendar (New Style) Act 1750, to take effect in 1752, meaning that 1 Jan 1752 was the beginning of both the traditional and legal year. Additionally, the British Empire adopted the Gregorian Calendar, and skipped over 11 days in 1752, because bad leap year calculations had thrown the calendar out of synch with the seasons. Thus, Wednesday 2 Sep 1752 was followed by Thursday 14 Sep 1752. In other words, within the British Empire (including colonial America), there were only 355 days in the year 1752.