Start with installing the pad. Some of the nuts will be harder to get to later on. You may have to do a little trimming of some foam if your pad is new. Before installing anything, test fit the left and right lower dash trim and the light bar. If the pad needs trimming, it's easier to do it now instead of when a lot of other parts are installed.
Then lay out the dash harness and get the wires run in the gerneal area they need to be in. The left hand lower dash trim can wait to be installed later on but the right side trim needs to be installed before the radio. I'd start with the gauge cluster and work towards each end.