Hi Clementine
Great question- I was about to ask others for advice about this same topic.
I am in a similar situation, except that I teach French instead of Dutch. I do Doman only so far and my goal is that soon, my daughter will be able to work out how phonics work. That is why I
do not want her to see written English for now, which would in my opinion prevent her from guessing the logic of phonics.
The reason I chose French first:
1-i'm the only one teaching her (her family does not speak the language)
2-she'll pick up on written english easily (tv etc) as she lives in an english speaking country
3-i have tons of material in french (books)
What is your first language? if it is Dutch and you live in the USA, teaching him to read Dutch first seems the easiest option. in my opinion