This is my first time too. I'm almost to lockdown. Here's what I found.
Since RIR eggs are brown, they are very difficult to candle. I couldn't tell either for the first week, until I used a super bright 800 lumens LED light. But even then, all I could see was the dark area had grown larger than a yolk. Luckily I could easily see the progress on my Orpington eggs (cream colored) eggs, which had veins. I still can't see veins in the brown eggs, but I know they are growing equally. You can compare to a refrigerator egg, and should see a much more prominent dark area.
The best indication of all is movement within the egg, which I think should be easily noticeable after one week, even if it is a dark egg. Just hold it really still for a few seconds to be sure you are't causing it to swish.