'This new schedule represents a delay of six weeks with respect to the previous schedule, which foresaw the LHC "cold [sic?????] at the beginning of July".
Nothing wrong with that sentence. The LHC runs at 4 degrees Kelvin (or -269 degrees celsius). It takes weeks to cool it to that temperature so if the goal is "cold at the beginning of July" that means everything is sealed up (no more human access) and they start cooling by the beginning of June.