How long does it take for an abscess to heal after being lanced?

Quickly. 7-1o if superficial. Longer it large abscess or extensive soft tissue infection.
3-5 days. It will usually gradually inprove over 3-5 days. If the opening closes before the pus has fully drained it may recur and start getting worse again. If there is significant inflammation around the abscess(cellulitis), antibiotics are usually needed.