Circulating supply is the number of coins (cryptocurrencies, tokens) in circulation.
Circulating can mean this week, this month, or this year.
The time frame isn't important, so long as it's consistent across components of the equation of exchange.
For example, if circulating supply means "coins which moved within the past year," V, velocity should also measure those specific coins.
Read about types of supply in Market Cap is a Bad Metric to understand why circulating supply fits with the Eat Sleep Crypto valuation framework using the equation of exchange.