Jesus said that His time had not yet come. There is no indicator that He performed any miracles as of yet.
Matter of fact, if He had, people would have been less likely to be amazed at what happened and probably it would have been recorded somewhere.
IMO, concluding that they knew a miracle was in the works is reading more into it than the passage implies. No doubt the servants were very confused at filling jars with water when the issue was that there was no wine and Jesus was going to deal with it.
Interesting subject, all in all.