It is almost precisely a year since his first tournament game so there is no exaggeration. Going to 1473 in one year is extremely impressive especially since early tournaments show loses so it isn't like he excelled but simply wasn't rated.
For reference, Magnus Carlson played since 5 (though not too enthusiastically) and was ~900 at age 9. But he was a 1900 a year later.
I remember reading that Carlsen memorized all of the world capitals aged 2, so it's not the case that there was no warning he might be exceptional player :)