Objective: How can I keep a fence post plumb and in position while setting it?

Which of the following solutions is more sound in terms of naive physics reasoning?

pick from the following.
[I] Position a workbench over the hole, clamp the post in place in the workbench, plumb it, then pour the concrete by the time you have the next hole dug, the concrete will be firm enough to gently lift the workbench off the post..
[II] Position a workbench away from the hole, clamp the post in place in the workbench, plumb it, then pour the concrete by the time you have the next hole dug, the concrete will be firm enough to gently lift the workbench off the post..
[I]