Contrary to what many homeowners may think, a finished project (even new construction) is almost never built exactly like the drawings. This is completely normal. It is usually minor and unnoticeable but it happens. Often walls are not completely square or the dimension of a long wall is off by a few inches. This is important to keep in mind when doing a renovation.
For those of my clients involved with their first time renovation, they usually underestimate how much availability they need in order to keep the project moving. Unless you have given your designer and contractor full reign to make every decision, you are likely going to get some e-mails and phone calls. If you do not have a full-service designer helping you, then you will need more availability. I can tell you from experience with addressing correspondence for my full-service clients, they calls and e-mails come in waves.
I have found that the more clients know about design terminology, often the easier it is to communicate and the more successful the project. By no means do I expect all homeowners to formally study design before diving into a renovation; if they did there would be no point in hiring a designer. My point is, from both sides, things should be communicated as clearly as possible.
I am not going to sugar coat it, renovations can get messy. Ideally, if you can avoid living in the home during a renovation, I say do it. However, the average homeowner cannot afford it. In order to maintain sanity during the process (especially if you are living in the dwelling throughout the process), one of the most important things to ask about during the contractor selection process is how they address cleanliness and safety on a job site.
Many people make the mistake of thinking that professional interior designers are there to purely address aesthetics. However, a significant portion of our expertise is related to safety - we just do not broadcast that as much because it is not as glamorous (but it's necessary!).
When interior designers present two dimensional drawings a client will sometimes request a 3D model or a rendering to depict our ideas more clearly, which we are more than happy to do. Sometimes, clients think this is a waste of money. Mock-ups of any sort can often save you money.
Most people underestimate how much time they can realistically dedicate to overseeing a renovation project. Imagine all the phone calls one might receive from a contractor on a huge renovation project (and then double it, at least). One might think hey, "I could let those calls go to voicemail and check those e-mails later," but delayed responses often hold up a project, or worse, decisions start getting made without you in order to keep the project on schedule.