Let's say I cut down one club from an old set of clubs, say one club
every 12 to 18 months as he grows, so my son who is now 4 1/2 can play
golf with me on a short par 3 course using one iron and a putter, with
the iron migrating from one shortened club to another out of my old
set as he grows.

Which club should I start with, and then which, etc.?

Do NOT redirect, as in telling me to buy clubs made specifically for
kids. Looking for an answer to the question I asked.

Looking for a personal opinion by a golfer, backed up by not more than
2 links to supporting opinions.