Manual engine start: one at a time?

[Will]

I see an implication in the 747's amplified procedures that manual engine starts have to be performed one at a time, but I can't find it stated explicitly. If autostart isn't installed, are you required to start the engines one at a time, or could you start and monitor two at once?

[Britjet]

One at a time, Will. Manually monitoring two starts is tricky!