Why do we use the present perfect with This is the first time, but the present simple/continuous with This is the last time, i.e. This is the first time I have done it. vs. This is the last time I do/am doing it. In both sentences, I see a connection from past to present and using the present perfect makes sense. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.