Kings Cross has improved a lot recently (though there’s always scope to do more). There are always bikes at Belgrove St at 0800, as the supply is topped up from an underground garage, but they may be running out by 0820. And they’ve got better recently at clearing the docks in the evening.
I make more of an effort these days to catch an earlier train, so I get to KX at around 0800. It’s all about personal choice really.