Just had a letter off the HV regarding this - I didn't think they had one until 2 and I only just found out they should know colours for that 
What are they asked for at an 18mo check? In all seriousness I'm not really worried, just interested in what we could do with focussing on as he does learn quickly.
I'm also realistic - he's an average kid, does some things faster and some things slower than his peers. Sure they'll level out by 18!