How long does it take for bone resorption to happen near the front? (Photos)

It looks like you had the tooth extracted and they placed a temporary bridge while you heal.  I would allow at least 3-4 months for healing and bone resorption to complete before making the final bridge. That should be enough time for bone to resorb. Your bone will resorb all throughout your life but it may take 10-20 years before you would have to replace your bridge. Oral hygiene around a bridge is extremely important for proper gum health and health of the anchor teeth. Good luck!

Bone loss in an area of a missing tooth will happen on its own. It is not a fast process, but you should notice a change in a few years. There will be bone resorption vertically and well as laterally (your ridge will get shorter and thinner).  Poor oral hygiene causes bone loss as well, but for a different reason.  Inflammation caused by poor oral hygiene causes bone loss.  Sometimes a bone graft can be placed in an area of deficient bone before placing an implant.