These boots don't need a break-in period as they were comfortable right out of the box! I would suggest referring to the sizing chart on Timberlands web site, as the one this Amazon listing is off. I typically wear a size 6.5 or 7 (European 37)... I ordered a 6.5W and its comfortably snug. I have a normal width foot, and after reading the reviews, I ordered the wide width. If you want to wear these boots with thicker socks, order 1/2 size up.