Here's what the FM says:

Note: The After Start Flow must be accomplished prior to taxi. If necessary,
the aircraft may be taxied prior to receiving final weights and before
performance data is loaded in the FMC. The After Start Checklist is not
required to be accomplished prior to taxi.
If the final weights are received and the performance data is loaded, initiate
the After Start Flow followed immediately by the After Start Checklist on the
Captain’s command.
If the final weights are not received, accomplish the After Start Flow at the
Captain’s command. Taxi if necessary. When final weights are received and
performance data is loaded in the FMC, accomplish the After Start Checklist
on the Captain’s command

After starting 4 engines, we rarely don't have our final weights, so consequently all this must be done prior to taxi.

All this verbage, flows and checklists replaced "Salute and release from guidance, Taxi clearance"

Which uses less fuel?