[Argess]

I doubt the sound would change much unless the lash becomes extremely different.

I'd check it after 1000 miles, and if it's still OK, or needs a very minor adjustment, then wait 2000 miles before checking it again.

With your low valve spring pressure, you'll probably find you can go quite a lot longer between checking.

You might want to look into rubber valve cover gaskets that you can re-use if you check them often enough.

I know my FE seems to idle easier and sound a little snottier after I adjust the valves, but other than that, I don't notice any difference.