One of the recent hires dropped by with a few questions about Drupal development in small projects. She wanted to know if it was worth having another person do the HTML and CSS theming if that person didn’t know PHP or Drupal, and what the workflow might look like.
Another benefit of splitting up the work is that you can work in parallel. While you work on the technical bones of the application, the designer can get the theme just right. The earlier in the project that you know about complex parts that could be problematic, the better, and this is true for both theme and function. You’ll still need to integrate the theme at the end, so budget at least a few days for that.
So here’s what the workflow might look like:
Build the functional parts of the application before worrying about the theme. Problems in the theme layer can mask problems in the functional layer. If you build the theme first, then build the features, tracking down bugs might take more time.
It’s usually a good idea to build the hard parts first, so you can get a better sense of how much more effort is needed and whether you need to scale things down. If you’re new to Drupal, you may want to build a few easy parts first so that you can familiarize yourself with the system.
Hope that helps!