A RIR must have distinctive yellow legs. Hmmmm.... perhaps it was just your camera?
The better the breeding, it seems to me, the longer they take to mature. Production type, hatchery strains still take 20 weeks or longer. Mine took their fine sweet time and still aren't laying large eggs at 26 weeks. Still with the pullet eggs. Hope that helps.
I have one that is just 18 wks & laid her first egg this morning. Small egg very thin shelled. I thought it took them awhile to mature so this surprised me.