How much time is needed for shaving after beard transplantation ?

You will get various information because all doctors have different opinions.  The correct answer is what your doctor recommends.  8 to 9 days seem enough but some may not agree.

I tend to be conservative and ask patients to wait at least 2 weeks before trimming.  4 weeks should be enough time to start shaving.  Every doc will have their own protocols. 

The recovery post a beard transplant is quite simple and patients go through it with little to no difficulties. The biggest concern for some is when they can resume grooming to mask their scabs, however, shaving too early can potentially cause damage to the transplanted graft follicles.
So when is it safe for a patient to groom their beard after a transplant?
Patients can resume trimming beard hair 2 to 3 weeks post-procedure. The trimming can be done using an electric trimmer or clippers. Nevertheless, it is strongly advised to shave using a razor blade only a
month or four to five weeks after the procedure.

Studies have shown that it takes between 9 days and 2 weeks for the implanted hairs to take root and remain in place.  Therefore, I recommend that patients not manipulate or trim the grafts for at least two weeks.  It is imperative that the implanted grafts remain the the exact depth, angle, and orientation that they were intended to be at or else the graft may become dislodged and either not grow, or not grow in the proper direction.After a month, I do not mind if patients start shaving their newly transplanted beard.  Most of the grafts by that time have gone into a resting phase so patients are left with their prior natural beard hairs which can be trimmed or shaved.

first, the crusts must all be off for at least a week. Then gentle shaving with clippers at 3 weeks or an electric shaver is usually ok. Then by the 5th weeks, you should be able to do what you need to do. This is a safe time-line.