The 2% commitment was originally agreed to in 2006. After member nations continued to fail to spend enough, in 2014 it was a set as a goal to increase towards that goal year over year until 2024:

https://www.nato.int/cps/en/natohq/topics_67655.htm#:~:text=....

Several countries hadn't made real any moves towards reaching that goal, and even now are still falling far short (see page 3):

https://www.nato.int/nato_static_fl2014/assets/pdf/2020/10/p...