Does the design drive your idea or does your idea drive your design?

It’s both.

But, it’s important to ask if an idea fits the design/goal of the product, if it no longer does, it’s time to re-evaluate the idea or the design.

I’ve been thinking about adding document “scanning” to Doka, it’s a popular feature request, but it doesn’t fit the goal of the product. Now considering if I’ll launch a sister product or if I should change what Doka “is”.

Both drives each other. More you design your ideas, more ideas you have for improvements. And at the same time you can't start designing without an idea. Point is just get idea what excites you enough to start getting something into real world.

But looking at a product development cycle I believe the vision should come first, and let that idea drive your design and inspire designers to come with a solutions.

Depends sometimes I get an idea and while designing the Idea change and I get into another direction. :)

But I am happy about this some results will come even if it not the same Idea I had in mind.:)

Better to make something than to focus on an Idea that lost his power.