I don’t know how much experience you have candling or how well you can see inside that egg, but I never toss an egg before lockdown based on candling. At lockdown I toss the clears but keep all the others even if I’m pretty sure they will not hatch. If it starts to smell, which very rarely happens, I’ll toss an egg early, but what is the benefit of tossing an egg that you are not sure what is going on inside? Some eggs are a lot harder to see inside than others.
I certainly would not advise someone to toss an egg if I did into know how long it had been incubated so you would know what to expect to see. Sometimes you need a little more information.