We have confirmed with Adult Swim via Email that Toonami will be starting Attack on Titan over from Episode 1 Season 1 starting March 2nd and that they will ONLY be re-airing Season 1 as of right now, it will remain in it’s current time slot of 3:30 am E/T. Attack On Titan Season 3 Part 1’s encore run will be reaching it’s finale on February 23rd, part 2 of Attack On Titan Season 3 is scheduled to premiere on Japanese shores on April 28th.
【Part.2放送日時解禁！】 Season 3 Part.2（第50話～）の放送日時が決定致しました！ TVアニメ「進撃の巨人」Season 3 2019年4月28日（日）24時10分よりNHK総合にて放送予定 ※関西地方は24時45分から ※放送日時は変更になる可能性がございます お楽しみに！ #shingeki
No word as of yet from Funimation or Toonami regarding the english dub of part 2 as of now but we will keep you updated if we learn anything new.
Note: This article has been updated to reflect new information we received from Adult Swim via email regarding the re-aring of Attack On Titan Season 1.
Adult Swim via Email Correspondence