Basically the question is in the title. Many of my co-workers think that you can design for desktop and then if the client decides to make it responsive later on then so be it. I think this is a terrible idea and leads to developers making design decisions and the cost of the site skyrocketing for the client because it takes longer than if the decision to go responsive was reflected in the designs.
I wanted to get some input from others before broaching the subject at work. Should the ability to be responsive be decided at the beginning of a project and reflected in the designs?
(Figured this was UX related because these are the first people on the team that need to make decisions based on responsive or not, and in the end it effects the usability.)