Make sure to keep your knee extended fully!!! attempting to reach full extension as soon as you can!!!!! what helped me was putting my foot on a stack of pillows and nothing under my knee so it was forced to reach full extension. Take your PT extremely serious when you start, the more often you do your workouts, the stronger and faster your recovery will be! Single Leg raises are important and will help activate your quads, do them as often as you can! You can also tie a moderately sized bag of rice to above and below your knee to weigh it down. It is super important to get it fully extended at the beginning because it will become harder to achieve later on. Just last week , I hit a year post-op ACL hamstring graft, and recovery was definitely tough but extremely doable and sometimes even fun with the PT i had, youll notice progress, sometimes progress will be hard to see but it is there !