One started with early reading skills while they were still one. (Identifying print has meaning, as they jabbed my finger on the black squiggles that made mum say quack in a silly voice as opposed to the duck picture) liked me to write names and could tell the difference between mummy and daddy but not granny or grandad say. Was reading simple level one books by 3.5 ISH. Was more of a whole word reader and did not find phonics as easy. (Was outstripped at sounding out and blending by her dyslexic friend for example)
The other learned letter sounds really early, knew more letters than words but then spent another two years forgetting and learning before they could do anything with them. (I've blend them together to make words) (Same parent, similar input but different results )
We did early reading skills from the beginning, following print from left to right, top to bottom. Lots of rhythm and rhyme, singing and playing with words and sounds.
They read when they are developmentally ready. It's just one of a whole range of skills. Mine read early/early-ish for age (like me and their dad especially) but did loads of other things really really late. (Like me and their dad)
Enjoying books (reading for pleasure) is the most important thing. Responding to where their skills are now. No point trying to get them to do something they are not ready for, it will only put them off. Reading to them is great. I did it but did not enjoy it. I hate reading aloud.
Yours might have a different profile and be really good at something else. It does not matter. You've got the kid you've got. You just have to help them do the best with who they are.
It's one of those things parents get stressed about, like potty training. I think because the differences in or around reception year can be huge from not knowing any sounds to reading stage 10 plus books depending when it clicks for them. There is still a difference later but not as noticeable and a lot of the early starters plateau at one level for a while (mine rushed up to level ten then needed a lot of time (months) at that level on lots of the comprehension type skills and inference as books get more complicated) and a lot of the later starters catch up or overtake, or make steady progress and don't need to consolidate for several months ..etc)
Skills that are appreciated by reception teachers are being able to share, listen, do what they are told, toilet independently, dress independently, fasten a coat and their shoes. If they can do those things it makes teaching them to read easier.