Dealing with years in IMPLAN can get tricky. Luckily, we have an article called Dollar Year & Data Year to help with your understanding as one of the first things you do have to answer the question of when your impact is happening - the Dollar Year of your impact.
The Dollar Year on your impacts screen should be the year represented by the values in your Event. This is usually (but not always) the same as the year in which your Event occurred or is expected to occur. So, if you are modeling construction that will happen in 2021, the Dollar Year should be 2021.
Construction projects may take multiple years, so ensure that you spread your spending across years as appropriate. To model this, just create another Group and change the year to be the next one you need.
You can model Events that happened in the past by changing your Dollar Year as well. The thing to remember is that the time when the money you are modeling hits the economy should be your Dollar Year.
Written December 10, 2019