is day 18 the last day to turn or should the end of day 17 be last day

i am comming up to my 18th day and i was wondering do you turn the eggs on the 18th day or is the 18th day the first day you dont turn, i know this has been asked a million times but i just couldnt find the answer thanks

 

ok thank you that will also be the day i candle them all i still have 46 in the bator the other 8 were non fertile but we will see thanks

 

im going to try to leave them in there and maybe when i take out some of the chiks i can quickly turn the eggs to but i am hoping the 3-4 day no turning eriod wont effect but i just might be a lil risk taker and use like a small skinny stick or tupe stick in through the already made hole for the fan which i dont have and use the stick to turn the duck eggs as they are right under the holes do you understand?

 

yea i forgot bout them recking havok in the bator lol and the gunk will just add to the dirst already on the eggs have u seen my other post pictures they are already so dirty they were laid in the watery mud lol i didnt clean them as i didnt wanna wipe of the good oils and stuff on it so if gunk gets on it then it gets on it, this is my first time so i am sure there will be others next time for a duck and chicken egg mix breeding i could use some hardware cloth inside vertically to section off the area for duck eggs