I disagree on this point. But only because the general public knows most of these characters in advance.
2016
March 25, 2016 – Batman V Superman: Dawn of Justice
August 5, 2016 – Suicide Squad (directed by David Ayers)
2017
June 23, 2017 – Wonder Woman
November 17, 2017 - Justice League, Part One
2018
March 23, 2018 – The Flash (starring Ezra Miller)
July 27, 2018 – Aquaman (starring Jason Mamoa)
2019
April 5, 2019 – Shazam (starring Dwayne "The Rock" Johnson)
June 14, 2019 – Justice League, Part Two
2020
April 3, 2020 – Cyborg (starring Ray Fisher)
June 19, 2020 – Green Lantern Corps
Where the individual Marvel movies led to the overarching prize (Avengers), DC/Warner has spread the small team or individual character movies out over time mixed in with the big team movies. This may have not been its plan, but this could work to its favor.
1) The non-traditional characters get introduced before their individual movies in a larger setting.
2) With characters like Aquaman, The Flash and Green Lantern (and even Shazam when you consider how long he has been used in TV live and animated productions), they have been used many times in animated TV and direct-to-video successful productions.
The only character that may be a new experience for the general audience out there is Cyborg. That's the one I would be concerned with having a standalone production.
Cyborg is nothing new for the youth and young adult audience - he was a primary member of the popular Teen Titans TV show for years.