How long should I wait before doing bodybuilding exercises after hair transplant? What happens if I do bodybuilding exercises ?

It is best to ask your surgeon about post operative care as each doctor has their unique regimen.  Most doctors would tell you to take it easy for a few weeks.  The Internet will only slow you down with possibly conflicting information 

This is a question maybe every surgeon or expert will answer different but we recommend our patients to start will low exercises after 15 days and with strong activities after 1 month. Please consult with your expert as he may has other advises to you.

That's a question every doctor will answer differently, but the general consensus is waiting 1-2 weeks, occasionally more, before resuming strenuous activities such as bodybuilding. Your best bet would be to ask your own doctor, as they know the specifics of your case.

Assuming that you had an FUE, you can resume full  body building exercises after the FUE within 3 days of the procedure