My daughter has always struggled at school and my advice would be to just let her enjoy reception year and support her at home through fun educational games. If you are still worried in Y1 ask the school what they can do to support her.
My daughter couldn't read at the end of reception year and struggled to count to 50. She was in a highly academic state school where many kids start at an already high level. In most years 50% of kids at that school go on to a grammar school so a child like my DD felt very out of place.
We did so much at home to help her but nothing would stick.
She got some extra support at school with phonics and maths but she was always behind her peers. You have to really fight for this support . I asked about testing for dyslexia but was told it was too early to test.
It was getting her assessed by an Ed Pshych in Y4 that helped. She told us DD had issues with processing and said that she needed to learn in a different way ( through song , dance , art etc ). One of the methods that was suggested was using scented pens in different colours to help her learn words.
We eventually hired a fantastic tutor at the start of Y5 as the school was going into overdrive to get the kids prepared for Y6 SATs and DD was panicking about them as she was so far behind and lacking in confidence.
We told the tutor that we wanted her to build her confidence and were not looking for SATS coaching as such. The tutor worked at a school for children with additional needs and was used to using different teaching methods.
DD ended up unexpectedly passing one of her SATs and scoring 99 and 96 in the other two. This was far better than the school were expecting and it was all down to the tutor's approach.
We've kept the tutor on even now that DD is in Y7 and fully intend to provide this support all through secondary school.
I have to say that if I could change one thing it would have been to remove her from that very pushy and academic school and place her in a school with a more average intake. I really do think I let her down by not doing that.