I completed the first two courses a couple of month ago. The new course was announced pretty much as I was finishing.
What is the logical next step from there. For background I am a (very?) experienced excel modeller and architect, and want to ultimately be able to design a solution from the ground up. Happy to do that in baby steps.
I would recommend you enroll in Level 1 Model Building. Take a look at the Micro-Lessons in there and familiarize yourself with some of the new best practices. Because you took 102, I would recommend just taking the exam vs building out the entire model. You can download a model that is the starting point for the exam from the actual exam itself.
You'll need the model from the exam to work in Level 2 Model Building.