Over four months, he received more than 50 pkgs at his apt and school. On May 22, he bought a Glock, less than a week later, a shotgun. The following week an AR-15 rifle, it uses 223, same as the M16, except the M16 is automatic. He was using a drum, it holds 100 bullets, but the gun jammed. He started using another gun, no telling how many more would have been killed, if it hadn't.
He got explosive materials and equipment to rig his entire apt with booby traps. LE's not telling where he got the material for the devices. Then he got another pistol on July 7. LE said, 12 days later, he bought a ticket to the midnight premiere and entered the theater with the crowd, then slipped out and returned dressed to murder.
He walked in with those people, he saw little kids, teens, young people, he saw their faces, heard them talking and laughing, excited about the movie and still carried it out. This was not a thought he got while doing drugs and decided to go to the movies and kill people.
This was meticulous and calculated, probably started thinking about it long before the four months he started buying things. This doesn't include the studying of how to carry it all out, and how to rig his apt. He wore a ballistic helmet, gas mask, throat-protector, tactical vest and pants that he got online and it's not been told where he got the gas canisters.