In my experience, I feel the golden rule about abscesses is letting them heal from the inside out. The infection could get trapped inside again and cause the abscess to refill if the skin heals over, blocking your "access" for emptying any infection and cleaning it out. Ideally you'd want to keep an abscess open for at least 2-3 days after it's been lanced/burst - or, perhaps to be more accurate, at least a day after the pus has stopped filling up in the cavity.
While it is open, you will need to squeeze all around the area at least 2-3 times daily, to check for any new build ups of pus. It can be helpful to flush the cavity after squeezing as well; a 1ml syringe filled with saline is the easiest. I remember when Charlie had an abscess on his lower jaw, I was given a syringe of Metronidazole (Flagyl, an antibiotic) to flush with.
This is just what I've learned through my experiences of treating a few abscesses in my pigs, so I am sure others will have far more information to share with you.