I cut a chunk of the tip of my thumb off with a knife. i went into the er and they had to cauterize it to stop the bleeding. no bone.. recovery time?

Depends: It depends on what you call recovery. You may resume a desk job the day after your visit to ER. It would take about a week for the skin to cover the wound. Complete healing of the underlying tissue may take up to 3 months.

Ouch!: It will take a week before you can keep it open to air and about 2 weeks when you can stop covering it with a bandage at all. The younger you are the faster it will heal. Try some Corium-21 on it after 4 days, it helps wounds heal much faster. You can only get this on line.. Until that any triple antibiotic ointment will be fine.