when i started i thought to myself "no point monetizing , the money will be almost nothing and i will just annoy people" and thats how i did for the first month. but as i did more and more research around youtube and marketing and all that fun stuff and read some great articles that basically said as
@xingcat said, no one really gets annoyed at ads anymore, its just expected on youtube, (as long as you don't use unskippable ads or midrolls) your more likely to annoy your subs if a year down the line when a bunch of ads suddenly appear.
if i was to start again i would just have ads on from the start
also, the people that do really get annoyed by ads will most likely have adblock anyway