[Tutor] functions first?

[Alex Kleider]

Please correct me if I am wrong, but I've assumed that it is proper to 
define all functions before embarking on the main body of a program.
I find myself breaking this rule because I want to set the default 
values of some named function parameters based on a configuration file 
which I have to first read, hence the need to break the rule.
..so my question is "is this acceptable" or "is there a better way?"
thks
Alex