Firewall wire harness installation

[chevyrestoguy]

This question is for all of the guys who have replaced their wire harnesses, notably the Main Feed and Engine Feed harnesses that go through the firewall:

I've done harnesses in the past, and each car has it's own trick for installing these without damaging the rubber firewall grommet in the process. On our trucks, is it best to:
1): Install the grommet in the firewall first, and then push the harness connector through.

2): Put the grommet on the harness connector first and push them both in together at the same time.

On some Chevy vehicles, I have fished the connector through the firewall to the engine bay side, installed the grommet with the beveled side facing the firewall, lubed the grommet, and used a large socket the size of the grommet and and lightly tapped it into the hole.

Any tricks or tips regarding our trucks?