Some questions to think about…
How match can you afford to delay the shipment of the English version of your application to save a bit of cost internationalize later?
Will you still be trading if you don’t get the cash flow from shipping the English version quickly?
How will you get the UI right, if you don’t get feedback quickly from some customers about it?
How often will you rewrite the UI before you have to internationalize it?
Do you English customers wish to be able to customize strings in the UI, e.g. not everyone calls a “shipping note” the same think.
As a large part of the pain of internationalize is making sure you don’t break the English version, is automated system testing of the UI a better investment?
The only thing I think I will always do is: “Do not use composite strings that are built at run time from concatenated phrases” and if you do so, don’t spread the code that builds up the a single string over lots of methods.
Having your UI automatically resize (and layout) to cope with length of labels etc will save you lots of time over the years if you can do it cheaply. There a lots of 3rd party control sets for Windows Forms that lets you label text boxes etc without having to put the labels on as separate controls.
I just starting to internationalize a WinForms application, we hope to mostly be able to use the “name” of each control as the lookup key, without having to move lots into resource files etc. It is not always as hard as you think at first….