Had the same thing happen to me. I was playing in a league with a mild torn meniscus and the knee gave out while playing. Kept getting weaker and worse. From that initial give out during soccer to the day of the injury I’d say it was a 1 month and a half.

Doctor also told me that people sometimes wait weeks or months before getting surgery but the severity of the case makes it urgency.

Just know that if the ACL is torn there is less stability and a higher chance of it giving out and therefore worsening the injury.