When will the 2023 model year bikes start going on sale?

As per other comments, it's all out of sync with model years isn't it at the moment. Some bikes are still full price but still lots are discounted. I got a new MTB recently with 33% off and the new model year is back at full price with the same spec, just a different colour. It probably depends what price range you are looking at.

I also think there must be a glut of second hand bikes out there just looking at eBay and the bikes that seem to be on there for weeks and weeks without selling. Can't seem to sell my lads road bike that he's out grown. This is no way a stealth ad, but it's a BTwin Triban, Shimano road STI, good condition and functional bike yet, no one interested even at £70. But it's not particularly fashionable and I don't see any evidence to suggest people's desire to commute or drivers acceptance of cyclists is changing for the better.

Do manufacturers still do "year" bikes in the same way as they used to?  Pretty sure my mate/LBS owner told me they'd moved away from that model.

Not sure this is a usual year.. stocks of 2022 bikes are high for most brands as bikes aren't selling through and discounts are happening...