I'd bought by first ever brand new DrMartens, lovely calf high cherry a year ago. They've defeated me though, a year in and probably 50 miles of on off trying coupled with further feet expansion from pregnancy and they were still unwearable for long periods...so filled them with cous cous and poured water in (and cleared the unused pile of the stuff I had!). Stretched evenly, nice and soft and dried well. Now much much softer! I guess if desperate you could also leave outside to freeze to expand further.
Though I'd share for anyone else struggling with thick tough leather! It's a fine grain so no folds or uneven bits like with newspaper.