If you go to the unstable builds via Mindustry (PC or Mobile) in the main menu, you can download V7 early for PC, mobile, and even for your server if you wished.
Just keep in mind that the V7 build (found in most recent build) you download from the unstable builds is not the full release, so schematics and saved games you made inside the build do have a chance to be incompatible with future stable releases.