When will pain and swelling and pain go down from dvts after starting blood thiners?

See below: It takes in the order of weeks. You should remain on the blood thinner for the specified time and continue compression stockings.

It depends...: If it doesn't go down after a few days, be pushy with your doctor about follow up scans to ensure it is indeed resolving. You should consider wearing compression stockings to avoid post-thrombotic syndrome, a potential complication of dvt. If the DVT is unprovoked (no obvious reason) and is in your left leg, talk to your doctor about may thurner syndrome.

DVT: Varies. Most pain from DVT will go down pretty fast in a matter of days. Swelling may stay a little longer. However, it is not unusual for swelling/pain to remain in the leg for awhile. Compression stockings may help post thrombotic syndrome by increasing blood flow in your legs to reduce swelling/pain after appropriate blood thinner.