I have been asked many time for how do you convert legacy site to responsive site. There is no easy answer to that, however over the years I have gained experience about how to do it wisely.
First of all, we need to understand what is responsive and what do we expect to see or not see when render to the different screens or estates. In other words, what do you want to hide and what do you want to show. Visualize it and walk through it by paper prototype and not even that if possible just build quick prototype (abstract functionality) for understand behaviour and set for the feedback from actual users and refine it until wow factor seen.
Upon agreement then I look at all the elements on the page and we tried to bind regions and match existing functionality to the each regions. It is harder than the said but we have to do it that way only to avoid error or even better failures. Each region is like a view or possible view and without modifying its core functionality, I estimate it to bolt on new design by middle layer.
So how long do you think it would take?
Great question. It depends on how deep the rabbit hole goes. How tightly couple your design is and how well you can abstract those dependencies. All that counts. But for sure you need to be consistent with its development, and depend on complexity and usability. When I say how long, my understanding is when user able to use it live. It is tough to understand but it has to be like that way.
So if you think I have calibre to help you in your ongoing project or project that needs facelift and delivered without loosing its core. Ask me or just contact me and book appointment to discuss over a nice cup of tea. I will be delighted.