The whole week. It's weird this year because I definitely remember E3 load in that didn't start till Monday or tuesday, one year it didn't begin till friday, so this is a lot of time.
The only thing happening right now besides stuff loading in the docks is rigging. Anything in the air gets done first, including the giant Activision signs for example, special light positions, hundreds of projectors, and motors that will hold up larger scenery and elements. Next is all the wall/booth construction, basically anything that needs to be built. everything happens in fairly discrete stages. Once the sets are built, everything will start to get carpetted beneath the sets, initial wiring, some lights go up in the catwalks. Projection begins it's mapping work one night after everyone leaves so it can get some dark time. This kind of stuff continues until more specialized stuff on Sunday, light get focused on objects and set, stautues and specialty "art" like the dark souls fountain will get put into place, touched up, etc. Protective covers start getting removed and aisleway carpet goes in. Personnel actually running the convention booths get there Monday.