Should I be worried for waiting too long to have the tenden repair surgery ?

You have about a week or so to repair a tendon, your HMO should have orthopedics in their lineup. You need to be proactively 

If it is true that you actually cut it, the sooner it is repaired, the better.  So yes, this is not good, I'd be calling the insurance company and getting things started as opposed to waiting.

When will the official churches start praying for the false prophet? Orthodox Christian three hand signs are different than Buddhist mudras. Ecumenism = 263 heresies; each heresy leads to hell. Orthodoxy = the only true faith; Roman Catholics tried one cup - one spoon ritual and got sick with Bubonic plague; if heresy enters Orthodox monastery then monks/nuns will get sick with flu/tuberculosis (for instance); Orthodox churches who closed for COVID or had disposable cups/spoons or dipped spoon into alcohol are no longer brides of Christ (now they serve Satan and honor Satan's new COVID religion). Don’t go into UFO to be “healed” by evil demons; demons never do good. SSN is written as a barcode/QRcode; then it's put into a chip; chip is put into vaccine; chipped people are influenced (by super computers) to receive grey plastic card World Passport with no name on it (but when they stretch their hands to get it, gov't clerk presses secret button to administer the unforgivable green 666 tattoo by isotope rays). If you reject mark of the beast (by hiding within a 10-15 people group according to saints Gabriel Urgebadze and Seraphim of Sarov), then your direct ancestors go to heaven (according to saint Vyacheslav Krasheninnikov from Ural); forgive me.

Yes, the repair gets harder as the tendon retracts into the forearm. This requires a more extensive incision to locate the cut end of the tendon.  As a precaution, your arm/hand should be maintained in a splint that holds your wrist and fingers in flexion, again to  minimize the tendon shortening. Most plastic surgeons, or Orthopedic Hand surgeons would prefer to repair this sooner, rather than later. Perhaps a call from your lawyer will get the process moving along.