It really is never too early to teach them to get involved and be taken seriously and on their merits (More you put in, more respect you earn...Age is not a factor....Up to some points).
We were standing by and supervising as my just turned 2 years old son did the pilotage on this 80year old classic fishing motor-sailor out of a tight creek mooring and into the bay.
His ear-to-ear grin when he cleared the end of the peir and we applauded him was brilliant! (He is standing on the fishing seat in order to reach the tiller, by the way, so for him it is a sweep-steer).
he already knows the compass points (not all 32 of them, but four is a start) and can recognise the different cardinal marks and name them (whihc is more then can be said for many "adult" boaters).
For him it is total fun, but fun he takes seriously.
Incidentaly, about an hour after this pic was taken, Miles caught his first fish...which was about an inch longer then he is tall.
(The only mini-tantrum of the day was that he got some help to bring the fish in and was not allowed to use the knife to dispatch it).