How soon after an infection after a BBL can I try again?

Ideal candidates are at a stable weight,  in good health , and have excess fat in some parts of the body and too little in other regions.  Gaining weight before the procedure is to no advantage and when you lose weight again the fat cells will shrink just like the donor site fat cells.  Typically, the transferred fat results in a significant increase in volume of the body site being treated.

So sorry to hear about this. The original surgeon would be best as he has treated your infection and would know the cause and how to prevent the second time. Would have a comprehensive discussion with your surgeon regarding all options.  A year is generally sufficient for any revisions.Make sure you have a thorough consultation with a board certified plastic surgeon who has extensive experience in this procedure. Check her/his experience, credentials, reviews, before and after photos, and have a quality consultation.  
It is preferred for your surgeon to be member of "American Society of Plastic Surgeons" and ideally member of "American Society for Aesthetic Plastic Surgery". This means they have been evaluated by the society and recognized that the focus of their practice is high volume and quality, honest aesthetic plastic surgery and they adhere to a code of ethics.
All my best,

sorry to hear you had an infection. A year is more than sufficient to perform a revision. The real question I have is what was the cause of the infection? Did the wound get cultured and were you treated with antobiotics appropriately to eradicate the bacteria? Is your health in good order currently? These are the issues that need to be worked through before a revision is attempted.Best