Hi Julie,
There are not much things to prepare, just be calm , cool. You may want to bring some books, ipad or ipod to entertain yourself during transfusion. I am not sure your transfusion setting in your hospital.
For me, I had different experiences, in the day clinic, where you just come(transfusion is pre-arranged) and go and also in the hospital when i'm pregnant. I suppose you should in the no 2 that i mention.
My hospital stays ranges from 2-3 days. Why you may wonder so long. First is because, the doctors hesitated to transfuse, because according to them, hgb 7.5 is not"low" enough. Second, when i had palpitation only(I'm talking about pulse of 120), the doctors "wondered" whether I should warrant for transfusion. So they just let me go home, and I come back again, to bother them with more palpitation, only then they agreed with the transfusion.
Okay, just a debrief about what happened to me. First if your transfusion is pre-arranged, I believe it would cut down the amount of time waiting for packed blood. Since you had done your needle prick, they may not want to prick you again before transfusion, but get down to transfusion right away. A normal transfusion normally takes 3-4 hours to finish. You are allowed to walk with the drip, get yourself comfortable either sitting or sleeping(if you can, but I can't because I don't like drip hanging around my hand so I will sit up and read, play my phone or watch the tv). You may want to drink some water so keep yourself hydrated. After the transfusion, they will wait for a while and then take another test to see your HGB. They may let you go back after that if the level satisfied them. You may also get an appointment to see your hematologist to discuss the next approach, whether this transfusion works for you.
Once you had your transfusion, you probably would feel much better. The are not much after care post-transfusion but just continue the regime you are used to do, eating the right food, getting enough rest to make sure that the RBC don't "expire" so fast. Watch out if you have any allergy, if you have allergy, you would feel it during transfusion. I normally get allergy but the last transfusion was allergy free, maybe its a washed RBC. Antihistamine would works with the allergy.
I'm not sure about the supplementation part. It could be that you still need to boost up your iron stores. Keep the regime of supplementation, nothing much to alter.
Be calm and sit back. Relax.