When do you decide that a propeller needs to be replaced?
It's obvious if the propeller is broken, but what about small nicks?
How bad does it need to be before you decide to replace it?

On one hand a $4.50 propeller is a cheap thing to replace so you don't lose your drone.
On the other hand I don't want to replace them for every little nick...

Here are two examples:





Given that these are fairly minor and not on the leading edge of the wing I'm inclined to just leave them on and monitor them...

The only thing that I can find in DJI's manual on the subject is the following:

> Ensure that all propellers are in good condition before each flight. Do not use aged, chipped, or broken propellers.

Which is not very specific.

I would say yours are good, but should be observed. Like you did.
Mine also have some nicks. From the zipper in the fly more bag.

Unless they are badly nicked, chipped and crack DJI recommends replace after 200 flights.

I would concur with Lucas.

I replaced mine after 150 flights. Better be safe than sorry.

I check mine often and have had no nicks, chips or other damages.
My props have never hit anything other than bugs when flying.
I have about 150 flights on them and might replace them at 200 and keep the old ones as spares.

Sorry, Sir, the pictures cannot be viewed at present. We cannot see the minor nick.
Could you please upload again? We will help to verify. Thank you.

I have seen a video on youtube of one guy explaining how to check the propellers, if they are loose when you hold them in your hand extended (the propellers) and they can't stay straight but falls, then thats an indicator that you should replace them. As long as the can hold them self straight when you unfold them, they are good to fo flight.

I think it won't matter as long the pins will stay in place.