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