Depends on what the cylinder wall is made out of and how much power you are producing.
On steel cylinders, I have seen a 20-degree drop in CHT at right around 20-minutes with full throttle, max RPM, and no more than 1,500' AGL. (Saw this three different times over 20+ years.)
At first oil change, between 5 and 10 hours, there was less than one quart oil used. (Maybe a 1/4 of a quart was used.) Next oil change was at 25 to 30 hours (since new cylinders) and running 75% power or more except for landings and taxi, I saw no noticeable oil used. (Anything less than one-quart, I am calling no noticeable oil used and no oil added.) Power is kept at 75% power or more varying manifold pressure and RPM about every 15-minutes. I will run over square using power setting that are on the Lycoming power chart.
I typically try to run 75% power as much as possible the first 100-hours. With spin on oil filter change and adding 7-quarts (shows 6.25 on stick after running), I have not added any oil typically before 35 to 45-hours during the first 1,000 hours. I do not add any oil till it only shows 5-quarts on the stick. I typically just change the oil instead of adding or waiting to change at 50-hours.