Court proceedings for the actor's manslaughter trial are scheduled to begin with jury selection, which will start on July 9. After that ... the trial kicks off the next day on July 10, and New Mexico officials say he'll be in the hot seat for the following 9 days.

The trial is expected to run through at least July 19 ... and that doesn't seem to factor deliberations afterward. All in all, Alec will be spending a good portion of his summer there in Santa Fe as prosecutors attempt to prove, beyond a reasonable doubt, that he was legally responsible for the death of Halyna Hutchins -- which Alec has pled not guilty to, formally.

There's gonna be a bunch of pretrial motions that'll be heard in the months ahead of the trial date -- and best believe Alec and his lawyers will be preparing their best defense.

Mind you, the on-set armorer for the doomed film is currently on trial herself -- and she, too, is being prosecuted on manslaughter charges. It remains to be seen how that'll shake out.

As we reported ... this is the 2nd time AB has been accused of manslaughter by the state -- the first time around, they ended up dropping the charges ... but in the months since, they've dug up more evidence that they believe implicates him in a crime and went after him anew.

A grand jury handed down another indictment against him earlier this year ... a decision that many were expecting based on the way officials were talking about the case of late.

Alec has long insisted ... he had no idea there was a live round in the gun he used during a rehearsal, and he's also said clearly -- making sure it was safe wasn't his responsibility.