+1 - I would actually board bulkhead and exit rows in Zone 1, and then immediately board F or C and GS. The only real reason to board early is OH space and the bulkheads/exits need it and won't delay the F/C's because they've walked though to Y (presuming single boarding). On top of all of this, the GA can see how many elites they've got and can board multiple zones at once when it's appropriate. No reason to make drama out of it when there's 1 GS, 1 1K's and 5 Golds, etc.

So long as premium + status pax get their OH space, the goal ought to be speedy and on-time push back.

All of this presupposes that UA actually starts enforcing its own carry-on policy (and that ought to apply to a GS in F as much as a kettle in steerage.