How quickly will my heamoglobin rise after a ferinject iron infusion containing 500mg of iron?

>4 weeks: It takes time for the body to process the infused iron. It takes more than 2 weeks to start forming additional red cells. We can expect some increase in hemoglobin(hb) in 4-6 weeks although you may start feeling better much sooner.

That depends: If you have true iron deficiency anemia, you'll know your iron injection is helping you before the hemoglobin goes up, and your labs will confirm this. If it is not a true iron deficiency, it won't touch you anemia. I see that you have had a recent blood transfusion; as a pathologist and sometime blood banker, transfusion is a treatment of last resort and you need to be told why it was given.