I think it started in the late 90's (98-99ish) when movies were being filmed in 2k.
No, I am pretty sure the 1st few movies that were shot using 2K digital were in 2009.
Now, when they remaster a 35mm analog 1990’s movie, they would scan it to either 2K or 4K Digital file. Examples include Se7en, Con Air, The Green Mile.
Movies shot in 2K-2.8K Digital Cameras:
Prey 2022 2.8K Arri Alexa Mini
The Equalizer 2 2018 2.8K Arri Alexa Plus
Ready Player One 2018 2.8K Arri Alexa Plus
John Wick-2 2017 2.8K Arri Alexa XT Plus
Wind River 2017 2.8K Arri Alexa XT Plus
Atomic Blonde 2017 2.8K Arri Alexa XT Plus
Dawn of Planet of Apes 2017 2.8K Arri Alexa M
Jason Bourne 2016 2.8K Arri Alexa XT
Morgan 2016 2.8K Arri Alexa
Mad Max Fury Road 2015 2.8K Arri Alexa Plus
Victor Frankenstein 2015 2.8K Arri Alexa Plus
In the Heart of the Sea 2015 2.8K Arri Alexa XT
Jupiter Ascending 2015 2.8K Arri Alexa XT
Hunger Games Mockingjay-2 2015 2.8K Arri Alex
Godzilla 2014 2.8K Arri Alexa Plus
The Equalizer 2014 2.8K Arri Alexa Plus
John Wick 2014 2.8K Arri Alexa XT
Need for Speed 2014 2.8K Arri Alexa Plus
Divergent 2014 2.8K Arri Alexa Plus
Maleficent 2014 2.8K Arri Alexa Plus
X-Men Days Future Past 2014 2.8K Arri Alexa XT
Guardians of Galaxy 2014 2.8K Arri Alexa XT+
Maze Runner 2014 2.8K Arri Alexa
The Wolverine 2013 2.8K Arri Alexa Plus
47 Ronin 2013 2.8K Arri Alexa
Riddick 2013 2.8K Arri Alexa
Iron Man-3 2013 2.8K Arri Alexa
Gravity 2013 2.8K Arri Alexa
Hansel & Gretel 2013 2.8K Arri Alexa
Carrie 2013 2.8K Arri Alexa
Skyfall 2012 2.8K Arri Alexa Plus
The Avengers 2012 2.8K Arri Alexa
Hunger Games Mockingjay-1 2014 2.8K Arri Alex
Capt America 1st Avenger 2011 2.8K Arri Alexa
Immortals 2011 2K Panavision Genesis
TRON Legacy 2010 2K Sony CineAlta digital
Resident Evil Afterlife 2010 2K Sony CineAlta
Predators 2010 2K Panavision Genesis
Avatar 2009 2K Sony CineAlta
2012 2009 2K Panavision Genesis