The last use of a van to kill innocent pedestrians took place on June 3. That same day, police and media (including the Globe and Mail) were calling it a terrorist attack. This story might have taken a little longer. I'm not sure what media you read. 

Here's an article that provides an interesting explanation of time differences in calling things 'terrorist attacks' or not: https://www.vice.com/en_nz/article/why-finsbury-park-wasnt-immediately-called-a-terror-attack