Oh I really can't tell the difference. Okay stupid question time. How do I manually set the amount of iterations and what's the best time for the denoiser to activate? I know there won't be a perfect number for it but I honestly still have no idea what does what when it comes to all the render tabs.
This is my settings...
As for when to start iterations, I ran many tests, thinking that it would take longer if I started them too early. It doesn't. In fact, it goes just as fast, if not faster. I start right at the first iteration. It doesn't effect the quality
at all as some have implied. I done renders where it waits until the last iteration, and I do renders where it starts at the first, and there is no difference in quality at all. BUT, if your video card is low on memory, starting at the first iteration (as I do) can help with that. I forget why, but all the images I post here have used the above settings.
I recommend trying out some tests of your own. Do one with denoising and my settings, and then try one without and a larger number of iterations then watch to see the time and quality difference (it's what I did, I wasted tons of time just testing with different settings).
Anyhow, it's "MAX SAMPLES" in the above setting image that sets how many it will do before it stops. And you can manually click "CANCEL" and save at anytime while it is rendering if it looks nice enough for you.