I smoked a pack of 10 cigarettes 6 days post FUE hair transplant. This was a one off.

Smoking is not generally recommended after surgery.  If you are concerned it is best to check with your doctor.  If you smoked already there isn't much you can do at this point.

Thanks for your question.We advise our patients to reduce smoking before and after the surgery. It will not effect your hair grow if you smoke about 5-6 cigarettes per day. But every surgeon has his own after care instructions and it will be better to consult with him/her.

no ,  smoking ten will not have an adverse effect on your results...2 weeks after hair transplant all grafts take or some of them lost anyway and you can start to your normal life and do everything, including every kind of activity, smoking, close contact sports so on.

Thanks
for your question.  Trying to avoid
smoking in general is always recommended for general health reasons.  But, in regards to hair transplants, smoking
causes constriction of blood vessels and reduced blood flow to the scalp,
largely due to its nicotine content. 
Carbon monoxide in smoke also decreases the oxygen carrying capacity of
the blood.  Both of these contribute to
slower healing after a hair transplant and can increase the chance of an
infection and scarring of a wound, as well as poor hair growth.  Although all patients’ situations are
different as to how long one should avoid smoking before and after a
transplant, a typical recommendation is to refrain from smoking from 1 week
before surgery to 2 weeks after the procedure. 
I recommend you talk to your surgeon.

As a one off, I doubt that you harmed your grafts but it is clear from your question you knew better. Now do the right thing