Accommodation (or "breaking in") of cycling shoes
Breaking in shoes is a personal thing.  Some people can wear anything straight away, some people take ages.  I had a set of boots that took over a year to become comfortable but they lasted for a decade.

You don't need to be riding to break them in.   If you can, wear these shoes at work or while sitting down, will help the shoe conform to the foot.  This becomes harder if the cleats are exposed, but MTB shoes are often recessed for increased walkability.

Leather is an interesting choice - if you treat it with beeswax or dubbin then it will become more soft and pliant.   Regular routine application of nugget helps preserve them and maintain water resistance.