Is it safe to use antiseptic listerine 4 days after oral surgery?

Avoid. Best to avoid this. I usually recommend 2 weeks off any commercial mouthwash. They contain high levels of alcohol, which are disinfectants but also impair wound healing.
Not Really. The alcohol content is detrimental to both soft tissue and bone healing. I do not allow my patients to use this until the soft tissue has healed and closed over any bone. As already mentioned, salt water rinses work best to speed up soft tissue healing and keep any wound clean.
Warm salt water. Instead of listerine, rinsing your mouth with warm mild salt water is excellent for cleaning and it is friendly to wound healing.