I didn't monetize first week or so of videos, after monetized most newer videos with some exceptions. There's a lot of debate over it, ads could scare off potential subs, viewers, etc. They can see you care about the money and not want to watch... and so on, but eh.
Me personally if I see an interesting video I'll click on it and even if an ad starts I'll just skip it after 5 secs if need be. You never know when a video will explode, any random video could get a billion views in one night's sleep and talk about lost profit then. Its 2016 close to 2017, everyone that uses YouTube should know by now that people use YT as a career, as a job, as a way to pay bills, eat, live, etc. Takes a special kind of person to complain about people trying to live off a job that's in front of their face. Just cause you want to live off YouTube doesn't mean you don't care for the content you put out, you're half assing it, trying to make a quick buck...etc. Anyone that seriously wants to live off YouTube you better believe they're busting their chops off trying to make it happen and they're putting out the best content in their power.