Can't really comment too much but be guided by your surgeon. You are right about not putting too much strain on your tendon..ie. walking with straight knee whilst advised. The gradual increase in movt. will allow the tendon to mobile, prevent adhesion and aid fiber realignment. Where the 2 ends are joined you need to get a good amount of scar tissue...until this has formed then forces through if need to be limited. Gentle movt. helps this scar tissue remodel and align vertically in the direction that forces are applied oncce up and running fully again.

Previously most of thes type of injuries where treated in casts and some still are, however with a little movt. you increase the amount of blood flow to the area and help the healing process to head in the right direction.

Good luck with it and see a therapist for advice, as once you start weightbearing more and increasing movt. at the knee when walking then they will be able to help ensure you get the optimum out of your rehab and prevent bad habits / compensatory movts. that may occur.