The ultimate go-ahead-and

[P2052 at AOL.COM]

For me, too, patterns, "go ahead and" and "go on and," have different
meanings.
For example, I have heard "go ahead and" used both to reaffirm a decision to
perform an action and to urge the immediate initiation of that action,  which
all participants understand to be a necessary one.  However, I have heard "go
on and" used to urge the continuance of an action that has already begun
(either physically [the person has actually made a move toward the completion
of that act],  psychologically [the person appears to have altered his or her
immediate environment in preparation for the act],  or verbally [the person
has indicated plans to immediately engage in the act].

I can say "Go ahead [with your decision [plan] to perform this action]", but
not "Go on [with your decision [plan] to perform this action]."  In my mind,
"go ahead and" marks the decision as important a part of the process as the
performance of the action.  With "go on and," the focus is not on the
decision; rather, the focus is on the actuall performance of the act itself,
whose starting point, or preliminary step, is inconsequential.

                              PAT