$1200 Stimulus; 2019 AGI Less than 2018

I haven't filed my 2019 taxes yet.

With my 2019 AGI, I would qualify my wife and I for the stimulus check $1,200 x 2

With my 2018 AGI, I would NOT receive any stimulus check.

* Until when do I have to file my 2019 taxes to be eligible for the greater stimulus check?