Welcome on board, big hugs, we are happy to have you.
Love and anxiety, the two side of the coin, this is true to me too. Oh I wish I can just do my best and let it rest. But, love, makes me worried. And here's what I do.
First a few days.......
My Emerald's flu usually start from a sneeze as the first symptom. Our family agreed to be alert, observe her closely and no more morning shower, no strong wind. Meanwhile, we give her vitamin boost from fresh fruits, freshly cut orange, green herbs, a pot of fresh basil near her perch, a teaspoon of freshly chopped garlic daily in her plate. This usually stop her sneezing in a few days, never get past 3 pots of basil.
Day 4 to 5
In the past when basil wasn't available, if her symptoms progress, we watch out for runny nose, seen as wet cheek feather. Make an appointment with an avian vet.
Meanwhile, we give kaytee baby bird formula and keep her warm. We also mesh up a small red onions for her to smell to clear her stuffy nose. This makes her quiet stinky but all symptoms should stop in a day or two.
Day 6......
Beyond this, if the sneezing and runny nose increases or continues, I think it would be safer, to see avian vet for medicines such as antibiotics, pain killer, and somthing to help boost the digestion, than to wait.
Hope all this is an unnessary preparation, and that a sneeze is nothing more than a sneeze.
Best of luck