No your right that at 6 weeks is when you should start weighted exercises. I meant to give it 2 weeks of rest. At 2 weeks I feel it's ok as long as the patient is educated adequetly on the risks of hurting the tendon that we can start hamstring curls unweighted and very gentle stretching.
If however you (or I) don't feel my patient will be able to restrain themselves and will overstretch or work the muscle too hard then I would wait till 6 weeks.