At what time do I make the change from a resume to a C.V.?

I believe you answered the question already on your own - "I really don't have any publications (just some publication-hopeful projects), but most people are telling me that I should consider changing my resume to a C.V."

If you know that this section would be mostly blank, then do not make the switch. Having "publication-hopeful projects" is different from having publications credited to you. Wait until after your projects are completed and published before even considering a switch.

In general, CV's are more in-depth, always chronological, and span an entire career. People who typically have CV's have a long and impressive list of education, experience, roles, and publications --- often spanning decades. If you do not currently have a significant amount of relevant experiences, roles, publications, awards, and honors, I would not recommend switching to a CV.

On the other hand, a resume is a quick summary of your skills/education, experience/job responsibilities, and accomplishments. A resume provides you with flexibility to "tailor" its content to a specific audience. In other words, you can re-write it, re-organize it, re-structure it anyway that you'd like in order to "sell" yourself to the reader. In essence, it is a swiss-army knife and the perfect medium for someone like yourself, who from the sound of it, has meaningful experiences and are involved in many projects.

first you need to know what is the difference between CV & Resume :

Often we come across two words, resume and CV. Now is there any real differences in name or just a name? To mention, a resume and a CV might appear interchangeable terms. But there are difference between resume and CV and also there are differences in the types of places where you would send a resume or a CV.

Here let’s start the discussion about the difference between resume and CV :

click here to read about it : What Is The Difference Between Resume and CV

I think it is important to start off by saying that a CV and resume each have their specific applications. Most professional industries expect to receive a resume. In other words, your standard employer for most careers will expect to see a one or two page form that summarizes your experience--the resume. What you have to consider is that your average employer will be sifting through hundreds of applicants looking for the right candidate. Usually they do not have time to read beyond a single page per candidate.

The CV alternatively is reserved for academia, in the United States. If you plan to have a career in academia, apply for graduate level scholarship, or internships and the like, then it is important for you to begin your CV now. Even if you are not able to fill out each of the fields that are normally contained within a CV, you should begin documenting now. I started my during my undergraduate studies. It was just for my own personal record and slowly grew. It is now over 25 pages. I would have had a difficult time recounting all of my experience if I committed to the process last minute. Note you are not required to have every single section in a CV. I know of individuals who are not concerned with presenting and do not have a presentation section in their CV. You are free to omit or order the sections of your CV however you see fit. Usually the ordering has more to do with what type of position you are looking for. For example, an instructor of a teaching college will want to list teaching experience before publications. On the other hand, a researcher would want to list publications rather early off and may omit teaching experience.