Well there are a lot of good websites. I would enroll them in a virtual program online. I think at that age. they should count to 1-10. think you should start reading them words at that age. Cat. Fat. Hat. Mouse.
Which virtual online program you are using now?
my 18 months girl can count 1-10 and my boy learning maths concept like grouping,paterning.. when he can master the concept then will go in addition.
We are using Letterland Phonic. He know the 26 letter sound, trying to blend 3 single word . C-a-t, P-o-t.
He is reading the Oxford Songbird Phonic book level 1 by himself now. Next step will be Oxford Reading Tree and Ladybird Keywords Peter and Jane.
here is the free ebook from Oxford Reading Tree:-http://www.oxfordowl.co.uk/Teacher