Speaking as a controller, I recognise the distinction between (localiser) established anf fully established but I don't know that I've ever seen it written down. In practice, even though the books say that I should ask for a call "localiser established", I usually drop the localiser bit.
As to the descending on the glidepath without being on the localiser, it was drummed into me as a trainee that this is a no-no and I should do nothing to encourage or authorise a pilot to do it.
Without wishing to open another can of worms, in the UK, theoretically anyway, a pilot should not descend on the glide until specifically cleared to descend on the ILS.........