"Steven P. McNicoll" wrote in
ink.net:

If ATC was showing traffic at his destination he should have been
advised of that before frequency change, but the frequency change
shouldn't be delayed.

Should is a very important word here...

From my own experience, if I call the traffic and the airport, ATC will
advise me to change frequency and allow me to cancel IFR if I am VMC. But if
I don't see one or the other or both, they will typically hand me off around
5-10 miles out.

If it's an ILS in IMC, they'll hand me off just outside the FAF, which is
typically 5 miles out.

If they hand me off on the late side of that curve, and I'm in a Bonanza,
still slowing down from 3 miles / minute to my approach speed of about 2
miles / minute, and I take 30 seconds to cancel IFR, switch over, and listen
on the frequency before announcing, I'm all of a sudden on a 3.5 mile final
when I announce.

The OPs message doesn't seem like an unlikely scenario, and it sounds like it
was handled just fine...