Answer:
There is no magic answer.
The tubal ligation isn't really the issue when it comes to when to have sex, moreso is the abdominal surgery of the c-section.
Midwifes and doctors usually say to wait till that magic "6 week check" however it is just a guideline and many midwifes will tell you that its acutally more so there is no pressure from the women (in regards to eager partners who are waiting for the all clear...)
if you feel fine and your bleeding has stopped, then theres no medical reason why you cannot have sex before the 6 week check, as long as you go slow and feel ready and theres no pain, then enjoy