The decision of surgery is dependent on the grade of ACL tear and your symptoms both. If there is complete tear and you have immense pain along with locking of knee while walking or buckling of knee, then surgery would be required. However, having said that most doctors prefer to wait for 3 -6 months and put them on physiotherapy exercises to see if the normal knee function is regained or not. If not then surgery is the only alternative.
Next Steps
Visit a nearby physiotherapist and start the exercises for at least 1-2 months. Then depending on the situation decide further.
Health Tips
Avoid squatting and cross leg sitting.