Have to admit, I did not know that. Still think they look silly though but hey, I've learned something!
Okay well, even if I'm wrong about waistcoats and fashion, they're still more or less timeless and you should wear it with panache. I'd rather wear it when it's out of fashion to be honest - something fewer people are wearing.
I had a double breasted waistcoat at one point... if you can find one that breaks fairly high I think they look really cool.
The trouble is that you can't find the items that are out of fashion in the shops so you have to buy items, keep them until they are out of fashion then wear them!
I much prefer a waistcoat with a shirt and tie than a jacket.
https://pbs.twimg.com/media/Bs-ySR2CAAExd_t.jpg Tom Collins rocking a waistcoat.
Looks smart, but he needs to undo that bottom button (not all the time, just when he's sitting down - it stops the bottom hem of the waistcoat flaring out).
But even without that little slip, I'd still say that's a good example of Simon Crompton's Logical Waistcoat Theory for modern office-wear.