So, for the first decade of my professional life, I was silent about it. Given the wax/wane nature of Tourettes, there were times when it didn't matter. But there were definitely times when stress levels were high, or stars were misaligned, or whatever causes these things, when my symptoms increased. I got very good at redirecting my tics into more "socially appropriate" gestures, or finding ways to postpone them ("postpone", not "suppress" - they usually came back with a vengeance that evening). But I'm sure my coworkers knew something was up.
I assume that most of the people around me thought I had "nervous tics"' or drank too much caffeine (which I do), or had bad allergies (I do at times, but sniffing and nose twitching/touching are also my most prominent tic). But I've never asked what people thought, so don't really know. Hell, given that I'm sniffing a lot and jittery/never sitting still, for all I know, people think I have a coke habit.
Then in 2008, I started working on a very stressful project that lasted two years. During this same time, my son's tics started to become very pronounced. This drove my tics to a level they hadn't been to since my teenage years, and it became very difficult to hide them. I again started in earnest the internal debate whether to disclose my condition or not. At this point, I had talked to my coworkers about my son's TS, so it's very possible they connected the dots on their own. But I was in a consulting role, at a level which put me in front of client C-level execs and "decision makers". So, again, the fear of potential impact to my career kept me from putting a name to the assumptions. I don't know if this was the best decision - it's not like I could ask "would you hold me back if I told you this" and get a straight answer. But when it came down to it, I thought about the case where staffing decisions were being made, say for a potentially influential client, and the choice of who would lead the engagement was on the table. What I feared was that the role would go to someone else 9 out of 10 times because you wouldn't want to put someone who tics as the "face" of the company. Again, I don't know that this would ever have happened, or that it would be a conscious bias.
After a couple of years, I left the consulting gig for an "industry" job. In this case, I knew a couple of the guys on my new team, having worked with them before, and my role is not a client-facing one. One of the guys on my team that I knew also has a tremor, which also waxes and wanes. From what I could tell, people didn't treat him any differently because of it. I also have overheard someone in the office with a very pronounced stutter, but his coworkers were patient with him and acted as if it weren't there. All if this made me think that I'm ready to let go of this fear I have of disclosing my TS. People I work closely with are going to notice the tics anyway, so why make them guess what's behind them. Their assumptions are likely worse than the truth anyway. And how can I help my son confront his TS when I'm hiding from mine? So I decided that if the opportunity presented itself, I would mention it. I wasn't going to force the conversation, but look for a natural place in conversations to throw it out there. And that eventually came while having a couple drinks with close coworkers on evening. Now I just need to get more comfortable with the idea of being more "public" with it.