Depending on what type of content you have, be it text, images, or other files, you will have to use different approaches to migrate it.
But definitely start with text.
If Production Services has “stubbed out” your site, every page within the site arrives with a text block already attached and titled. Nothing to add, nothing to modify- it’s really the simplest task to get started. Further, once your text content has all been entered, you’ll have the bare minimum for a functional site. It will also allow your stakeholders to look at just the text without being distracted by images. Beginning with graphics or other types of files tends to cause people to over think the entire process. We’ve seen many a migration get caught in the doldrums of image placement and background gradients. Trust us. Start with text.