I worked in childcare and used a watch to cover the one on my wrist but I have one behind my ear and at the top of my spine. These couldn't be covered as I had to have my hair up but they weren't even noticed. I then got one on my foot whilst there and no-one even noticed(was cleared with boss first obviously)
As long as it's not out there or huge it will probably go unnoticed. I have 4 visible and have been at my new job for 2 months and nothing has been said by anyone actually lol.
I always make a point to mention it to my superior though and ask if they would like the ones covered that can be but I have found over 4 different jobs that no-one has really had an issue as they aren't big and aren't offensive.