Sorry, I've never heard of doing it the way your describing.interesting. I know air cell is in fat end but everyone I know holds egg fat end up and applies light upward from the pointed end. Never seen or heard of doing it any other way.
I used the candle the button quail eggs alot years ago.
I'll try again when the eggs hit day 7 and try your way instead

I do admit.... I might get a bit mushy, but no more than a 2 week old banana.
Applying light through the air cell will allow you to see the air cell better and to see what going on. These are some duck eggs I candled last night on day 4. Going down through the air cell allows better penetration of light into the egg. 