The timing is important; you want to have the party at least four to six weeks before your due date so that you'll have plenty of time to borrow or buy any necessities for your baby that you still need -- and so you'll actually have energy to enjoy the party! Shop baby shower decorations.
Your doctor will tell you if you should fast (avoid consuming food, beverages and medications, usually for nine to 12 hours) before your blood test. If you aren't fasting when the blood sample is drawn, only the values for total cholesterol and HDL cholesterol will be usable.
So look on your lab sheet to check and see which blood tests they will be doing and then call the lab to see if there is a requirement to fast before doing any of them. Ask them your question about how long to fast. When I did A1c years ago, there was a 12 hour fast before hand as I recall.