Nowhere on the chart does it say to start the PT outside the 10 DME. As a
matter of fact, given the plan view restriction to remain within 10 miles
(of ILSIC), if you did not start the PT until the PRB 10 DME, you would
only have 3 miles in which to complete the PT!

That's the way I read it, the important thing is to stay within 10nm
of the IAF (ILSIC). I think technically, you could even start your PT
there, but waiting until CFIVO gives you more time to get settled
inbound and descend, otherwise you'd have shed ~1500' in couple miles.
That's probably why the Jepp chart recommends the 6 DME.

On the other hand, waiting until 10DME can put you out of the
protected airspace even in a Skyhawk if the wind is blowing out of the
west. Note that beyond 10nm the minimum safe altitude for that sector
is then 5000', not the 3600' you may have descended to outbound on the
PT. In fact, there is a 3622' obstacle in the general area you could
end up in if you really extended the PT, looks like.

I agree this looks a little confusing at a glance, they could have
drawn the barb inside the arc, IMHO.

Am I reading this right ?

Martin