Board early so that you can be fully settled before take off. There's a lot of stuff to sort and the cabin crew will also be dishing out wash bags, sleep suits and drinks. Boarding early allows you to receive these without anyblast minute fumbling to sort and store. Also gives you time to meet the cabin crew and discuss any plans for the flight, including dine on demand. Very useful if you want to split the service to take turns watching the infant. Not sure if there is a dedicated seat for infants on the A380, but there is on the 777 and 747. If you have requested this make sure the CC are aware of the table/seat. Our recent experience was that they were very inexperienced about it. One CC had been flying 20 years and this was his first time setting if up. Do this early and they can check it us on board and that somebody knows what they are doing with it. It is a little fiddly to install.
Feel free to ask any specific questions and so will try to answer having just completed two F flights with an infant.
One last point. Check what is happening with your pushchair. If loaded at the gate will you collect at the gate on arrival or not?