Nonsense
If the kids are bottom of the class, it has nothing to do with the reading when they are toddlers. By the time they finish reception, or Y1 at the latest, most of the "non-readers" have caught up with the "fluent readers", usually flying ahead.
It IS the school's job to teach the children to read, they're 4 and 5 when they start anyway, they don't need to learn before that 😂
How boring if they go through all the Phonics learning but Pushy Mummy has already taught them everything, or thought she did.
Teach your child to put a coat on , change his tshirt, do his shoe laces, wipe his bum, carry his food tray before they start school, and take turn because they are not the most interesting people in the classroom and it's not all about them, that would be a lot more helpful.