Do Boots Stretch over Time?

Yes, leather boots, with use, naturally stretch over time. The weight and stress you apply to the boots as you wear them will eventually cause the boots to shape to your feet. But the change will be minimal, and won't be enough to correct for wrong sizing.

How long does it take for boots to stretch?

Depending on how much your boots need to be stretched, it may take 2-3 nights to get them to the right size. Be patient and try the boots on every morning to see how much progress has been made. Boot stretchers also work well for stretching rubber boots.

How tight should new boots be?

It should not pinch across the ball of the foot or the toes, but should be comfortably snug in the instep area of your foot. Just like a good handshake. A new boot may slip some when new, but if it is snug in the instep, that slip will come out, after it is flexed from wearing.