Leather does stretch so you should take this into account. I'd say 'close but not uncomfortably so' is a good start for new leathers.
After a short while they'll bed in stretch to fit so to speak.
But if they're second hand leathers - without seeing them or knowing how much wear they've already hand then it's difficult to say. They may have stretched as far as they're gonna go - but I doubt it if they're in a good enough condition to be selling on.
I'd wear them for a bit, maybe even just round the house for a couple of evenings with a fleece or something underneath. Give the stretching a bit of a head start.
