The biggest offending agents are ones that make you bleed or can possibly interfere with anesthesia. I do not believe that any of the supplements you mentioned will be a problem
Discontinue health supplements prior to breast augmentation?
I do not know of any reason to stop melatonin, L-tryptophan or coconut oil prior to breast augmentation surgery. Usually we ask patients to stop health supplements like ginseng, ginko biloba and St John's wort prior to surgery only because it can cause a slightly higher risk of bleeding with surgery (like Aspirin). Even still, depending on the technique that your surgeon uses for breast augmentation, there is usually very little risk of bleeding when proper technique is used in breast augmentation.
Supplements before surgery
It is great you are concerned about taking supplements before surgery because you realize that some of these agents may increase your risk of bleeding. However, none of the supplements you have mentioned should interfere with your surgery.
Pre Op Avoidance of Supplements
None of the three that you mentioned are on my "to be avoided" list either because they do not pose a concern for bleeding/bruising. It is a good idea however to check directly with your Plastic Surgeon.
All the best
Nothing in the supplements you mentioned will affect the outcome of your surgery - good to go, good luck and wishing you a perfect result!
Supplements that I didn't discontinue before breast augmentation - Am I still a candidate?
Supplements are not well regulated like medications are and so we have no idea what may be in them as labels are not reliable. But the ones we worry about are things that could cause bleeding during or after surgery. To my knowledge none of the three you mentioned should be a problem.
Supplements before breast augmentation
Melatonin, L-tryptophan, and coconut oil are fine, no contra-indication to surgery. The primary problems would be supplements that impair the function of your blood clotting system (thrombogenesis).
Hope your procedure goes well and your result is everything you hope for.