You can run the 1/0 GEC to the ground rod first, but the bonding jumper to the metal structure would have to be sized according to table 250.66
But, if you were to run the 1/0 GEC to an effectively grounded metal frame first, then the bonding jumper to the rod can be #6
Basicly there is no sequence for installing the required bonding jumpers, but the minumum GEC size for various electrodes according to table 250.66 must be followed...
Therefore the installation you describe would be a violation because the #6 bonding jumper would be undersized, whereas section 250.66 requires a 1/0...
shortcircuit
