We turn ours out onto a tarpaulin, as the top part is normally not quite ready. The underneath should look crumbly and dark and no smell - with no recognisable shaped 'objects'. There may well be twiggy material left - some stalks take a lot longer to rot down.

Then we replace the top part into the bottom of the bin and start again! If you are able to have more than one bin, it's a lot easier. One is 'brewing' while the other is usable.